[DevTools] Clear DatabaseClient's pointer to InspectorDatabaseAgent on detach.

[DevTools] Clear DatabaseClient's pointer to InspectorDatabaseAgent on detach.

This should not matter in regular case, as the Page, DatabaseClient and
InspectorDatabaseAgent all have the same lifetime.
But it looks like we can have DevTools initialized twice for the page in OOPIF case.

BUG=526162
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201569

[dgozman, 2015-08-31 19:36:53]

dgozman@chromium.org changed reviewers:
+ dcheng@chromium.org, pfeldman@chromium.org

[dgozman, 2015-08-31 19:36:54]

Could you please take a look?

I'm not sure this is the right fix. At least this fixes the bots, and _should_
not harm anything. It's a follow up to the patch, which is suspicious itself:
https://codereview.chromium.org/1307323006/diff/1/Source/web/WebDevToolsAgent....
If you have any ideas/comments on the original one, please tell.

Thanks,
Dmitry

[dcheng, 2015-08-31 19:42:06]

Any idea where the double-init is happening?

[dgozman, 2015-08-31 20:27:42]

On 2015/08/31 19:42:06, dcheng wrote:
> Any idea where the double-init is happening?

Here is the stack.

#0 0x00000154a5be base::debug::StackTrace::StackTrace()
#1 0x00000154a0ff base::debug::(anonymous namespace)::StackDumpSignalHandler()
#2 0x7f1b5a056340 <unknown>
#3 0x00000398df3d blink::DatabaseClient::setInspectorAgent()
#4 0x000003998e9b blink::InspectorDatabaseAgent::InspectorDatabaseAgent()
#5 0x000003792ef6 blink::InspectorDatabaseAgent::create()
#6 0x00000378f758 blink::WebDevToolsAgentImpl::create()
#7 0x0000037c90e0 blink::WebLocalFrameImpl::setDevToolsAgentClient()
#8 0x0000009808c7 content::DevToolsAgent::DevToolsAgent()
#9 0x000000998623 content::RenderFrameImpl::Initialize()
#10 0x00000099851b content::RenderFrameImpl::CreateFrame()
#11 0x0000009e1b78 content::RenderThreadImpl::OnCreateNewFrame()
#12 0x0000009f1050
_ZN4base20DispatchToMethodImplIN7content16RenderThreadImplEMS2_Fv24FrameMsg_NewFrame_ParamsEJS3_EJLm0EEEEvPT_T0_RKNS_5TupleIJDpT1_EEENS_13IndexSequenceIJXspT2_EEEE
#13 0x0000009f0f55
_ZN4base16DispatchToMethodIN7content16RenderThreadImplEMS2_Fv24FrameMsg_NewFrame_ParamsEJS3_EEEvPT_T0_RKNS_5TupleIJDpT1_EEE
#14 0x0000009e6a2b FrameMsg_NewFrame::Dispatch<>()
#15 0x0000009e15ad content::RenderThreadImpl::OnControlMessageReceived()
#16 0x00000542981d content::ChildThreadImpl::OnMessageReceived()
#17 0x0000016a7937 IPC::ChannelProxy::Context::OnDispatchMessage()

[dcheng, 2015-09-01 00:32:23]

this patch lgtm to fix the crash, but let's make sure we follow up and figure
out where this double initialization is happening

[dgozman, 2015-09-01 00:53:46]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2015-09-01 00:53:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1323443004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1323443004/1

[commit-bot: I haz the power, 2015-09-01 01:02:41]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-01 01:02:42]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[pfeldman, 2015-09-01 01:05:18]

lgtm

[dgozman, 2015-09-01 01:07:03]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2015-09-01 01:07:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1323443004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1323443004/1

[commit-bot: I haz the power, 2015-09-01 01:14:48]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-01 01:14:49]

Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[dgozman, 2015-09-01 18:03:11]

The CQ bit was checked by dgozman@chromium.org

[dgozman, 2015-09-01 18:03:11]

The patchset sent to the CQ was uploaded after l-g-t-m from dcheng@chromium.org,
pfeldman@chromium.org
Link to the patchset: https://codereview.chromium.org/1323443004/#ps20001
(title: "Fixed tests")

[commit-bot: I haz the power, 2015-09-01 18:03:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1323443004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1323443004/20001

[commit-bot: I haz the power, 2015-09-01 19:55:18]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-01 19:55:19]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[dgozman, 2015-09-01 20:25:38]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2015-09-01 20:25:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1323443004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1323443004/20001

[commit-bot: I haz the power, 2015-09-01 21:16:36]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201569