Attachment #256256 for bug #146657

View Details Raw Unified Return to Bug 146657



2015-07-06  Brent Fulgham  <bfulgham@apple.com>

        [WK2] UIProcess/WebProcess shutdown logic may have race condition
        https://bugs.webkit.org/show_bug.cgi?id=146657
        <rdar://problem/21693748>

        Reviewed by NOBODY (OOPS!).

        Logging changes to help debug this problem.

        * Platform/IPC/Connection.cpp:
        (IPC::Connection::createSyncMessageEncoder):
        (IPC::Connection::sendMessage):
        (IPC::Connection::postConnectionDidCloseOnConnectionWorkQueue):
        (IPC::Connection::connectionDidClose):
        (IPC::Connection::sendOutgoingMessages):
        * Platform/IPC/mac/ConnectionMac.mm:
        (IPC::ConnectionTerminationWatchdog::watchdogTimerFired):
        (IPC::Connection::sendOutgoingMessage):
        * Shared/ChildProcess.cpp:
        (WebKit::ChildProcess::messageSenderDestinationID):
        (WebKit::ChildProcess::terminationTimerFired):
        (WebKit::ChildProcess::stopRunLoop):
        * Shared/ChildProcessProxy.cpp:
        (WebKit::ChildProcessProxy::state):
        (WebKit::ChildProcessProxy::sendMessage):
        (WebKit::ChildProcessProxy::shutDownProcess):
        * UIProcess/WebPageProxy.cpp:
        (WebKit::WebPageProxy::setFormClient):
        (WebKit::WebPageProxy::setUIClient):
        (WebKit::WebPageProxy::close):
        (WebKit::WebPageProxy::webProcessWillShutDown):
        * UIProcess/WebProcessProxy.cpp:
        (WebKit::WebProcessProxy::connectionWillOpen):
        (WebKit::WebProcessProxy::processWillShutDown):
        (WebKit::WebProcessProxy::removeWebPage):
        * WebProcess/WebPage/WebPage.cpp:
        (WebKit::WebPage::exitAcceleratedCompositingMode):
        (WebKit::WebPage::close):
        (WebKit::WebPage::tryClose):
        (WebKit::WebPage::didReceiveMessage):
        * WebProcess/WebProcess.cpp:
        (WebKit::WebProcess::didReceiveMessage):
        (WebKit::WebProcess::didClose):

2015-07-06  Brent Fulgham  <bfulgham@apple.com>

        Ensure media playback is stopped during page close

Lines 344-353 std::unique_ptr<MessageEncoder> Connecti Source/WebKit2/Platform/IPC/Connection.cpp_sec1
- Source/WebKit2/Platform/IPC/Connection.cpp -2 / +17 lines
344	return encoder;	344	return encoder;
345	}	345	}
346		346
		347	#include <syslog.h>
		348
347	bool Connection::sendMessage(std::unique_ptr<MessageEncoder> encoder, unsigned messageSendFlags, bool alreadyRecordedMessage)	349	bool Connection::sendMessage(std::unique_ptr<MessageEncoder> encoder, unsigned messageSendFlags, bool alreadyRecordedMessage)
348	{	350	{
349	if (!isValid())	351	if (!isValid()) {
		352	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::sendMessage >>>: %s. INVALID connection. Bailing out.", encoder ? encoder->messageName().data() : "(null)");
350	return false;	353	return false;
		354	}
351		355
352	if (messageSendFlags & DispatchMessageEvenWhenWaitingForSyncReply	356	if (messageSendFlags & DispatchMessageEvenWhenWaitingForSyncReply
353	&& (!m_onlySendMessagesAsDispatchWhenWaitingForSyncReplyWhenProcessingSuchAMessage	357	&& (!m_onlySendMessagesAsDispatchWhenWaitingForSyncReplyWhenProcessingSuchAMessage
Lines 703-710 void Connection::postConnectionDidCloseO Source/WebKit2/Platform/IPC/Connection.cpp_sec2
703	});	707	});
704	}	708	}
705		709
		710	#include <syslog.h>
		711
706	void Connection::connectionDidClose()	712	void Connection::connectionDidClose()
707	{	713	{
		714	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::connectionDidClose >>>");
		715
708	// The connection is now invalid.	716	// The connection is now invalid.
709	platformInvalidate();	717	platformInvalidate();
710		718
Lines 733-738 void Connection::connectionDidClose() Source/WebKit2/Platform/IPC/Connection.cpp_sec3
733		741
734	RefPtr<Connection> connection(this);	742	RefPtr<Connection> connection(this);
735	RunLoop::main().dispatch([connection] {	743	RunLoop::main().dispatch([connection] {
		744
		745	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::connectionDidClose >>>: Runloop dispatch for didClose handling. Connection client is (%p)", connection->m_client);
		746
736	// If the connection has been explicitly invalidated before dispatchConnectionDidClose was called,	747	// If the connection has been explicitly invalidated before dispatchConnectionDidClose was called,
737	// then the client will be null here.	748	// then the client will be null here.
738	if (!connection->m_client)	749	if (!connection->m_client)
Lines 744-749 void Connection::connectionDidClose() Source/WebKit2/Platform/IPC/Connection.cpp_sec4
744	Client* client = connection->m_client;	755	Client* client = connection->m_client;
745	connection->m_client = nullptr;	756	connection->m_client = nullptr;
746		757
		758	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::connectionDidClose >>>: Runloop dispatch calling didClose on client (%p)", connection->m_client);
		759
747	client->didClose(*connection);	760	client->didClose(*connection);
748	});	761	});
749	}	762	}
Lines 755-762 bool Connection::canSendOutgoingMessages Source/WebKit2/Platform/IPC/Connection.cpp_sec5
755		768
756	void Connection::sendOutgoingMessages()	769	void Connection::sendOutgoingMessages()
757	{	770	{
758	if (!canSendOutgoingMessages())	771	if (!canSendOutgoingMessages()) {
		772	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::sendOutgoingMessages >>> Can't send. Returning.");
759	return;	773	return;
		774	}
760		775
761	while (true) {	776	while (true) {
762	std::unique_ptr<MessageEncoder> message;	777	std::unique_ptr<MessageEncoder> message;

Lines 62-68 static const size_t inlineMessageMaxSize Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm_sec1
- Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm -2 / +7 lines
62	enum {	62	enum {
63	MessageBodyIsOutOfLine = 1 << 0	63	MessageBodyIsOutOfLine = 1 << 0
64	};	64	};
65		65
		66	#include <syslog.h>
		67
66	// ConnectionTerminationWatchdog does two things:	68	// ConnectionTerminationWatchdog does two things:
67	// 1) It sets a watchdog timer to kill the peered process.	69	// 1) It sets a watchdog timer to kill the peered process.
68	// 2) On iOS, make the process runnable for the duration of the watchdog	70	// 2) On iOS, make the process runnable for the duration of the watchdog
Lines 87-92 private: Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm_sec2
87		89
88	void watchdogTimerFired()	90	void watchdogTimerFired()
89	{	91	{
		92	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "!#!#!#!#!#!#! ConnectionTerminationWatchdog::watchdogTimerFired !#!#!#!#!#!#!#!: Killing process.");
90	xpc_connection_kill(m_xpcConnection.get(), SIGKILL);	93	xpc_connection_kill(m_xpcConnection.get(), SIGKILL);
91	delete this;	94	delete this;
92	}	95	}
Lines 284-291 bool Connection::sendOutgoingMessage(std Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm_sec3
284	char* buffer = &stackBuffer[0];	287	char* buffer = &stackBuffer[0];
285	if (messageSize > inlineMessageMaxSize) {	288	if (messageSize > inlineMessageMaxSize) {
286	buffer = (char*)mmap(0, messageSize, PROT_READ \| PROT_WRITE, MAP_ANON \| MAP_PRIVATE, -1, 0);	289	buffer = (char*)mmap(0, messageSize, PROT_READ \| PROT_WRITE, MAP_ANON \| MAP_PRIVATE, -1, 0);
287	if (buffer == MAP_FAILED)	290	if (buffer == MAP_FAILED) {
		291	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< Connection::sendOutgoingMessage >>>: %s. MMAP failed. Returning without sending.", encoder ? encoder->messageName().data() : "(null)");
288	return false;	292	return false;
		293	}
289	}	294	}
290		295
291	bool isComplex = (numberOfPortDescriptors + numberOfOOLMemoryDescriptors > 0);	296	bool isComplex = (numberOfPortDescriptors + numberOfOOLMemoryDescriptors > 0);

Lines 140-155 uint64_t ChildProcess::messageSenderDest Source/WebKit2/Shared/ChildProcess.cpp_sec1
- Source/WebKit2/Shared/ChildProcess.cpp -1 / +8 lines
140	return 0;	140	return 0;
141	}	141	}
142		142
		143	#include <syslog.h>
		144
143	void ChildProcess::terminationTimerFired()	145	void ChildProcess::terminationTimerFired()
144	{	146	{
145	if (!shouldTerminate())	147	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcess::terminationTimerFired >>>");
		148	if (!shouldTerminate()) {
		149	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcess::terminationTimerFired >>> shouldTerminate is FALSE");
146	return;	150	return;
		151	}
147		152
		153	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcess::stopRunLoop >>>: TERMINATING");
148	terminate();	154	terminate();
149	}	155	}
150		156
151	void ChildProcess::stopRunLoop()	157	void ChildProcess::stopRunLoop()
152	{	158	{
		159	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcess::stopRunLoop >>>");
153	RunLoop::main().stop();	160	RunLoop::main().stop();
154	}	161	}
155		162

Lines 87-92 ChildProcessProxy::State ChildProcessPro Source/WebKit2/Shared/ChildProcessProxy.cpp_sec1
- Source/WebKit2/Shared/ChildProcessProxy.cpp -1 / +12 lines
87	return ChildProcessProxy::State::Running;	87	return ChildProcessProxy::State::Running;
88	}	88	}
89		89
		90	#include <syslog.h>
		91
90	bool ChildProcessProxy::sendMessage(std::unique_ptr<IPC::MessageEncoder> encoder, unsigned messageSendFlags)	92	bool ChildProcessProxy::sendMessage(std::unique_ptr<IPC::MessageEncoder> encoder, unsigned messageSendFlags)
91	{	93	{
92	switch (state()) {	94	switch (state()) {
Lines 99-107 bool ChildProcessProxy::sendMessage(std: Source/WebKit2/Shared/ChildProcessProxy.cpp_sec2
99	return connection()->sendMessage(WTF::move(encoder), messageSendFlags);	101	return connection()->sendMessage(WTF::move(encoder), messageSendFlags);
100		102
101	case State::Terminated:	103	case State::Terminated:
		104	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::sendMessage >>>: Unable to send message: %s. state is Terminated", encoder->messageName().data());
102	return false;	105	return false;
103	}	106	}
104		107
		108	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::sendMessage >>>: Unable to send message: %s. state is not Launching, Running, or Terminated.", encoder->messageName().data());
105	return false;	109	return false;
106	}	110	}
107		111
Lines 153-164 void ChildProcessProxy::didFinishLaunchi Source/WebKit2/Shared/ChildProcessProxy.cpp_sec3
153		157
154	void ChildProcessProxy::shutDownProcess()	158	void ChildProcessProxy::shutDownProcess()
155	{	159	{
		160	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::shutDownProcess >>>: state is %d, connection is (%p)", state(), m_connection.get());
		161
156	switch (state()) {	162	switch (state()) {
157	case State::Launching:	163	case State::Launching:
158	m_processLauncher->invalidate();	164	m_processLauncher->invalidate();
159	m_processLauncher = nullptr;	165	m_processLauncher = nullptr;
		166	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::shutDownProcess >>>: state is Launching");
160	break;	167	break;
161	case State::Running:	168	case State::Running:
		169	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::shutDownProcess >>>: state is Running. Calling connection->terminateSoon(30)");
162	#if PLATFORM(IOS)	170	#if PLATFORM(IOS)
163	// On iOS deploy a watchdog in the UI process, since the child process may be suspended.	171	// On iOS deploy a watchdog in the UI process, since the child process may be suspended.
164	// If 30s is insufficient for any outstanding activity to complete cleanly, then it will be killed.	172	// If 30s is insufficient for any outstanding activity to complete cleanly, then it will be killed.
Lines 167-172 void ChildProcessProxy::shutDownProcess( Source/WebKit2/Shared/ChildProcessProxy.cpp_sec4
167	#endif	175	#endif
168	break;	176	break;
169	case State::Terminated:	177	case State::Terminated:
		178	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::shutDownProcess >>>: state is Terminated. Doing nothing.");
170	return;	179	return;
171	}	180	}
172		181
Lines 175-182 void ChildProcessProxy::shutDownProcess( Source/WebKit2/Shared/ChildProcessProxy.cpp_sec5
175		184
176	processWillShutDown(*m_connection);	185	processWillShutDown(*m_connection);
177		186
178	if (canSendMessage())	187	if (canSendMessage()) {
		188	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::shutDownProcess >>>: sending Message::ChildProcess::ShutDown");
179	send(Messages::ChildProcess::ShutDown(), 0);	189	send(Messages::ChildProcess::ShutDown(), 0);
		190	}
180		191
181	m_connection->invalidate();	192	m_connection->invalidate();
182	m_connection = nullptr;	193	m_connection = nullptr;

Lines 563-568 void WebPageProxy::setFormClient(std::un Source/WebKit2/UIProcess/WebPageProxy.cpp_sec1
- Source/WebKit2/UIProcess/WebPageProxy.cpp +4 lines
563	m_formClient = WTF::move(formClient);	563	m_formClient = WTF::move(formClient);
564	}	564	}
565		565
		566	#include <syslog.h>
		567
566	void WebPageProxy::setUIClient(std::unique_ptr<API::UIClient> uiClient)	568	void WebPageProxy::setUIClient(std::unique_ptr<API::UIClient> uiClient)
567	{	569	{
568	if (!uiClient) {	570	if (!uiClient) {
Lines 811-816 void WebPageProxy::close() Source/WebKit2/UIProcess/WebPageProxy.cpp_sec2
811		813
812	m_webProcessLifetimeTracker.pageWasInvalidated();	814	m_webProcessLifetimeTracker.pageWasInvalidated();
813		815
		816	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "#### WebPageProxy::close ####: Sending WebPage::Close() message to page %llu", m_pageID);
814	m_process->send(Messages::WebPage::Close(), m_pageID);	817	m_process->send(Messages::WebPage::Close(), m_pageID);
815	m_process->removeWebPage(m_pageID);	818	m_process->removeWebPage(m_pageID);
816	m_process->removeMessageReceiver(Messages::WebPageProxy::messageReceiverName(), m_pageID);	819	m_process->removeMessageReceiver(Messages::WebPageProxy::messageReceiverName(), m_pageID);
Lines 3535-3540 void WebPageProxy::connectionWillOpen(IP Source/WebKit2/UIProcess/WebPageProxy.cpp_sec3
3535		3538
3536	void WebPageProxy::webProcessWillShutDown()	3539	void WebPageProxy::webProcessWillShutDown()
3537	{	3540	{
		3541	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< WebPageProxy::webProcessWillShutDown >>>: Calling m_webProcessLifetimeTracker.webProcessWillShutDown.");
3538	m_webProcessLifetimeTracker.webProcessWillShutDown();	3542	m_webProcessLifetimeTracker.webProcessWillShutDown();
3539	}	3543	}
3540		3544

Lines 146-151 void WebProcessProxy::connectionWillOpen Source/WebKit2/UIProcess/WebProcessProxy.cpp_sec1
- Source/WebKit2/UIProcess/WebProcessProxy.cpp -2 / +11 lines
146	page->connectionWillOpen(connection);	146	page->connectionWillOpen(connection);
147	}	147	}
148		148
		149	#include <syslog.h>
		150
149	void WebProcessProxy::processWillShutDown(IPC::Connection& connection)	151	void WebProcessProxy::processWillShutDown(IPC::Connection& connection)
150	{	152	{
151	ASSERT_UNUSED(connection, this->connection() == &connection);	153	ASSERT_UNUSED(connection, this->connection() == &connection);
Lines 162-169 void WebProcessProxy::processWillShutDow Source/WebKit2/UIProcess/WebProcessProxy.cpp_sec2
162	callback();	164	callback();
163	m_pendingDeleteWebsiteDataForOriginsCallbacks.clear();	165	m_pendingDeleteWebsiteDataForOriginsCallbacks.clear();
164		166
165	for (auto& page : m_pageMap.values())	167	for (auto& page : m_pageMap.values()) {
		168	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< ChildProcessProxy::processWillShutDown >>>: Calling page->webProcessWillShutDown.");
166	page->webProcessWillShutDown();	169	page->webProcessWillShutDown();
		170	}
167		171
168	releaseRemainingIconsForPageURLs();	172	releaseRemainingIconsForPageURLs();
169	}	173	}
Lines 228-233 void WebProcessProxy::addExistingWebPage Source/WebKit2/UIProcess/WebProcessProxy.cpp_sec3
228		232
229	void WebProcessProxy::removeWebPage(uint64_t pageID)	233	void WebProcessProxy::removeWebPage(uint64_t pageID)
230	{	234	{
		235	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "#### WebProcessProxy::removeWebPage ####: Removing page %llu", pageID);
		236
231	m_pageMap.remove(pageID);	237	m_pageMap.remove(pageID);
232	globalPageMap().remove(pageID);	238	globalPageMap().remove(pageID);
233		239
Lines 241-249 void WebProcessProxy::removeWebPage(uint Source/WebKit2/UIProcess/WebProcessProxy.cpp_sec4
241		247
242	// If this was the last WebPage open in that web process, and we have no other reason to keep it alive, let it go.	248	// If this was the last WebPage open in that web process, and we have no other reason to keep it alive, let it go.
243	// We only allow this when using a network process, as otherwise the WebProcess needs to preserve its session state.	249	// We only allow this when using a network process, as otherwise the WebProcess needs to preserve its session state.
244	if (!m_processPool->usesNetworkProcess() \|\| state() == State::Terminated \|\| !canTerminateChildProcess())	250	if (!m_processPool->usesNetworkProcess() \|\| state() == State::Terminated \|\| !canTerminateChildProcess()) {
		251	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "#### WebProcessProxy::removeWebPage ####: We CANNOT shut down the WebProcess for page %llu. Because (a) uses network process? (%d), (b) state() == State::Terminated? (%d), (c) Can terminate process? (%d)", pageID, m_processPool->usesNetworkProcess(), state() == State::Terminated, canTerminateChildProcess());
245	return;	252	return;
		253	}
246		254
		255	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "#### WebProcessProxy::removeWebPage ####: We are allowed to shut down the WebProcess for page %llu. Doing so.", pageID);
247	shutDown();	256	shutDown();
248	}	257	}
249		258

Lines 642-649 void WebProcess::didReceiveMessage(IPC:: Source/WebKit2/WebProcess/WebProcess.cpp_sec1
- Source/WebKit2/WebProcess/WebProcess.cpp +4 lines
642	LOG_ERROR("Unhandled web process message '%s:%s'", decoder.messageReceiverName().toString().data(), decoder.messageName().toString().data());	642	LOG_ERROR("Unhandled web process message '%s:%s'", decoder.messageReceiverName().toString().data(), decoder.messageName().toString().data());
643	}	643	}
644		644
		645	#include <syslog.h>
		646
645	void WebProcess::didClose(IPC::Connection&)	647	void WebProcess::didClose(IPC::Connection&)
646	{	648	{
		649	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< WebProcess::didClose >>>: Received didClose");
		650
647	#ifndef NDEBUG	651	#ifndef NDEBUG
648	m_inDidClose = true;	652	m_inDidClose = true;
649		653

Lines 913-920 void WebPage::exitAcceleratedCompositing Source/WebKit2/WebProcess/WebPage/WebPage.cpp_sec1
- Source/WebKit2/WebProcess/WebPage/WebPage.cpp +7 lines
913	m_drawingArea->setRootCompositingLayer(0);	913	m_drawingArea->setRootCompositingLayer(0);
914	}	914	}
915		915
		916	#include <syslog.h>
		917
916	void WebPage::close()	918	void WebPage::close()
917	{	919	{
		920	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< WebPage::close >>>: Closed state: %d", m_isClosed);
		921
918	if (m_isClosed)	922	if (m_isClosed)
919	return;	923	return;
920		924
Lines 1004-1009 void WebPage::tryClose() Source/WebKit2/WebProcess/WebPage/WebPage.cpp_sec2
1004	return;	1008	return;
1005	}	1009	}
1006		1010
		1011	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< WebPage::tryClose >>>: Sending Message::WebPageProxy::ClosePage(true)");
1007	send(Messages::WebPageProxy::ClosePage(true));	1012	send(Messages::WebPageProxy::ClosePage(true));
1008	}	1013	}
1009		1014
Lines 3617-3622 void WebPage::didReceiveMessage(IPC::Con Source/WebKit2/WebProcess/WebPage/WebPage.cpp_sec3
3617	}	3622	}
3618	#endif	3623	#endif
3619		3624
		3625	syslog(LOG_MAKEPRI(LOG_SYSLOG, LOG_CRIT), "<<<<< WebPage::didReceiveMessagee >>>: Got a message: %s", decoder.messageName().data());
		3626
3620	didReceiveWebPageMessage(connection, decoder);	3627	didReceiveWebPageMessage(connection, decoder);
3621	}	3628	}
3622		3629

Return to Bug 146657

Lines 1-3 Source/WebKit2/ChangeLog_sec1
- Source/WebKit2/ChangeLog +45 lines
		1	2015-07-06 Brent Fulgham <bfulgham@apple.com>
		2
		3	[WK2] UIProcess/WebProcess shutdown logic may have race condition
		4	https://bugs.webkit.org/show_bug.cgi?id=146657
		5	<rdar://problem/21693748>
		6
		7	Reviewed by NOBODY (OOPS!).
		8
		9	Logging changes to help debug this problem.
		10
		11	* Platform/IPC/Connection.cpp:
		12	(IPC::Connection::createSyncMessageEncoder):
		13	(IPC::Connection::sendMessage):
		14	(IPC::Connection::postConnectionDidCloseOnConnectionWorkQueue):
		15	(IPC::Connection::connectionDidClose):
		16	(IPC::Connection::sendOutgoingMessages):
		17	* Platform/IPC/mac/ConnectionMac.mm:
		18	(IPC::ConnectionTerminationWatchdog::watchdogTimerFired):
		19	(IPC::Connection::sendOutgoingMessage):
		20	* Shared/ChildProcess.cpp:
		21	(WebKit::ChildProcess::messageSenderDestinationID):
		22	(WebKit::ChildProcess::terminationTimerFired):
		23	(WebKit::ChildProcess::stopRunLoop):
		24	* Shared/ChildProcessProxy.cpp:
		25	(WebKit::ChildProcessProxy::state):
		26	(WebKit::ChildProcessProxy::sendMessage):
		27	(WebKit::ChildProcessProxy::shutDownProcess):
		28	* UIProcess/WebPageProxy.cpp:
		29	(WebKit::WebPageProxy::setFormClient):
		30	(WebKit::WebPageProxy::setUIClient):
		31	(WebKit::WebPageProxy::close):
		32	(WebKit::WebPageProxy::webProcessWillShutDown):
		33	* UIProcess/WebProcessProxy.cpp:
		34	(WebKit::WebProcessProxy::connectionWillOpen):
		35	(WebKit::WebProcessProxy::processWillShutDown):
		36	(WebKit::WebProcessProxy::removeWebPage):
		37	* WebProcess/WebPage/WebPage.cpp:
		38	(WebKit::WebPage::exitAcceleratedCompositingMode):
		39	(WebKit::WebPage::close):
		40	(WebKit::WebPage::tryClose):
		41	(WebKit::WebPage::didReceiveMessage):
		42	* WebProcess/WebProcess.cpp:
		43	(WebKit::WebProcess::didReceiveMessage):
		44	(WebKit::WebProcess::didClose):
		45
1	2015-07-06 Brent Fulgham <bfulgham@apple.com>	46	2015-07-06 Brent Fulgham <bfulgham@apple.com>
2		47
3	Ensure media playback is stopped during page close	48	Ensure media playback is stopped during page close