Added Ash.TimeBetweenTaskSwitches to record time deltas between all recorded task switches.

Added Ash.TimeBetweenTaskSwitches to record time deltas between all recorded task switches.

TEST=TaskSwitchMetricsRecorderTest.VerifyTaskSwitchesRecordInAllTaskSwitchHistogram

BUG=487745
Committed: https://crrev.com/490726475af73f0eb82c320adc33dacc972e84c9
Cr-Commit-Position: refs/heads/master@{#333658}

[bruthig, 2015-06-02 15:42:29]

bruthig@chromium.org changed reviewers:
+ asvitkine@chromium.org, oshima@chromium.org, tdanderson@chromium.org

[bruthig, 2015-06-02 15:42:30]

tdanderson@chromium.org: Can you please have a look from a feature correctness
point of view?
 - */*

asvitkine@chromium.org: Please review changes in 
 - tools/*
 - ash/metrics/task_switch_metrics_recorder.cc

oshima@chromium.org: Please review changes in 
 - ash/*

[tdanderson, 2015-06-02 15:56:12]

lgtm with nits below

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
File ash/metrics/task_switch_metrics_recorder.h (right):

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:25: // Task switches between any two
other sources. NOTE: This value should NOT
nit: suggested reword: "Task switches caused by any of the sources in this enum"
?

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:56: // used and behavior is undefined
if it is.
Include in the documentation of OnTaskSwitch() that it does two things: notifies
of a task switch corresponding to the specific source passed in, and also
notifies of an "any" task switch.

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:60: // Internal Implementation of
OnTaskSwitch(TaskSwitchSource) that will accept
nit: lower-case i on implementation.

https://codereview.chromium.org/1148723006/diff/1/tools/metrics/histograms/hi...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/1148723006/diff/1/tools/metrics/histograms/hi...
tools/metrics/histograms/histograms.xml:856: +   
Ash.WindowSelector.TimeBetweenActiveWindowChanges, etc).
Since this list is (currently) exhaustive, perhaps change the e.g. to i.e. and
drop the etc. ?

[Alexei Svitkine (slow), 2015-06-02 21:31:58]

lgtm

[oshima, 2015-06-02 23:47:58]

lgtm

[bruthig, 2015-06-04 17:53:30]

Responded to tdanderson@'s comment in tools/metrics/histograms/histograms.xml.

tdanderson@, can you take a look?

https://codereview.chromium.org/1148723006/diff/1/tools/metrics/histograms/hi...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/1148723006/diff/1/tools/metrics/histograms/hi...
tools/metrics/histograms/histograms.xml:856: +   
Ash.WindowSelector.TimeBetweenActiveWindowChanges, etc).
On 2015/06/02 15:56:12, tdanderson wrote:
> Since this list is (currently) exhaustive, perhaps change the e.g. to i.e. and
> drop the etc. ?

The reason I chose to have the 'etc' is because I doubt this description will be
kept up to date if a new task switch action is tracked.  I'd feel better keeping
it as an "e.g." and making the list non-exhaustive...  what do you think?

[bruthig, 2015-06-04 18:54:26]

tdanderson@, can you take a look at the updated documentation?

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
File ash/metrics/task_switch_metrics_recorder.h (right):

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:25: // Task switches between any two
other sources. NOTE: This value should NOT
On 2015/06/02 15:56:12, tdanderson wrote:
> nit: suggested reword: "Task switches caused by any of the sources in this
enum"
> ?

Done.

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:56: // used and behavior is undefined
if it is.
On 2015/06/02 15:56:12, tdanderson wrote:
> Include in the documentation of OnTaskSwitch() that it does two things:
notifies
> of a task switch corresponding to the specific source passed in, and also
> notifies of an "any" task switch.

Done.

https://codereview.chromium.org/1148723006/diff/1/ash/metrics/task_switch_met...
ash/metrics/task_switch_metrics_recorder.h:60: // Internal Implementation of
OnTaskSwitch(TaskSwitchSource) that will accept
On 2015/06/02 15:56:11, tdanderson wrote:
> nit: lower-case i on implementation.

Done.

[tdanderson, 2015-06-04 21:59:39]

lgtm with a micro nit

https://chromiumcodereview.appspot.com/1148723006/diff/20001/ash/metrics/task...
File ash/metrics/task_switch_metrics_recorder.h (right):

https://chromiumcodereview.appspot.com/1148723006/diff/20001/ash/metrics/task...
ash/metrics/task_switch_metrics_recorder.h:52: // task that becomes active is
user-predictable (ie Alt+Tab accelerator,
micro-nit: ie -> e.g., here and at line 56.

[bruthig, 2015-06-05 19:27:24]

The CQ bit was checked by bruthig@chromium.org

[bruthig, 2015-06-05 19:27:25]

The patchset sent to the CQ was uploaded after l-g-t-m from
asvitkine@chromium.org, oshima@chromium.org, tdanderson@chromium.org
Link to the patchset: https://codereview.chromium.org/1148723006/#ps40001
(title: "Addressed tdanderson@'s micro-nit.")

[commit-bot: I haz the power, 2015-06-05 19:28:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148723006/40001

[commit-bot: I haz the power, 2015-06-05 19:33:23]

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

[commit-bot: I haz the power, 2015-06-05 19:33:24]

Try jobs failed on following builders:
  linux_chromium_compile_dbg_32_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[bruthig, 2015-06-09 22:31:01]

The CQ bit was checked by bruthig@chromium.org

[bruthig, 2015-06-09 22:31:01]

The patchset sent to the CQ was uploaded after l-g-t-m from
asvitkine@chromium.org, oshima@chromium.org, tdanderson@chromium.org
Link to the patchset: https://codereview.chromium.org/1148723006/#ps60001
(title: "Merged with master.")

[commit-bot: I haz the power, 2015-06-09 22:33:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148723006/60001

[commit-bot: I haz the power, 2015-06-10 02:28:38]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-06-10 02:29:24]

Patchset 4 (id:??) landed as
https://crrev.com/490726475af73f0eb82c320adc33dacc972e84c9
Cr-Commit-Position: refs/heads/master@{#333658}