DevTools: tracing: remove state management from InspectorTracingAgent.

DevTools: tracing: remove state management from InspectorTracingAgent.

Tracing state management happens on the browser side. So the local state does nothing.
Also if DevTools window was closed when tracing was active the next DevTools session had
this flag enabled. So it was not possible to correctly process tracing data because they
had no TracingStartedInPage event. The state used to be necessary when we had console.timeline/timelineEnd implementation.

This test case has been covered by timeline-trivial.html

BUG=420008
R= yurys@chromium.org, caseq@chromium.org, pfeldman@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=183608

[caseq, 2014-10-13 08:31:14]

lgtm

[vsevik, 2014-10-13 12:03:39]

vsevik@chromium.org changed reviewers:
+ vsevik@chromium.org

[vsevik, 2014-10-13 12:03:39]

lgtm

[loislo, 2014-10-13 12:41:17]

The CQ bit was checked by loislo@chromium.org

[commit-bot: I haz the power, 2014-10-13 12:42:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/638673002/1

[commit-bot: I haz the power, 2014-10-13 12:52:53]

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

[commit-bot: I haz the power, 2014-10-13 12:52:54]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/2...)

[loislo, 2014-10-13 14:01:51]

The CQ bit was checked by loislo@chromium.org

[commit-bot: I haz the power, 2014-10-13 14:02:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/638673002/140001

[commit-bot: I haz the power, 2014-10-13 15:04:19]

Committed patchset #2 (id:140001) as 183608

[yurys, 2014-10-15 08:43:47]

https://codereview.chromium.org/638673002/diff/140001/Source/core/inspector/I...
File Source/core/inspector/InspectorTracingAgent.cpp (left):

https://codereview.chromium.org/638673002/diff/140001/Source/core/inspector/I...
Source/core/inspector/InspectorTracingAgent.cpp:44: if
(m_state->getBoolean(TracingAgentState::tracingStarted)) {
I believe we'd better return an error when tracing is already started. It can be
determined at this point by checking whether
m_state->getString(TracingAgentState::sessionId) is empty.

https://codereview.chromium.org/638673002/diff/140001/Source/core/inspector/I...
Source/core/inspector/InspectorTracingAgent.cpp:58:
m_state->setBoolean(TracingAgentState::tracingStarted, false);
This is not enough as after front-end disconnect we will still have non-empty
sessionId in the state. We should clear it on front-end disconnect.

[yurys, 2014-10-15 08:46:23]

https://codereview.chromium.org/638673002/diff/140001/Source/core/inspector/I...
File Source/core/inspector/InspectorTracingAgent.cpp (left):

https://codereview.chromium.org/638673002/diff/140001/Source/core/inspector/I...
Source/core/inspector/InspectorTracingAgent.cpp:44: if
(m_state->getBoolean(TracingAgentState::tracingStarted)) {
On 2014/10/15 08:43:46, yurys wrote:
> I believe we'd better return an error when tracing is already started. It can
be
> determined at this point by checking whether
> m_state->getString(TracingAgentState::sessionId) is empty.

It can be a DCHECK since we reject such requests on the browser side:
https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/de...