tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bc46ae630f07dc43b5a2ede866f028b3360112c5..0c5cbad83db1c94fd3013282df2b0a9269c9ec7f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -3579,6 +3579,35 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time spent on 2D canvas putImageData API call.</summary>
 </histogram>
 
+<histogram name="Blink.Canvas.ToBlob.IdleEncodeDuration" units="microseconds">
+  <owner>junov@chromium.org</owner>
+  <owner>xlai@chromium.org</owner>
+  <summary>
+    Time spent on encoding on the idle period of the main thread.

[Ilya Sherman, 2016/06/30 07:35:51]

Sorry, this is still unclear to me.  Encoding and idle just don't make sense to
me in combination, since encoding seems like it would, by definition, not be
idle.  I'd suggest asking a teammate to help you clarify this description -- I'd
happily offer suggestions, but I'm really not sure what the intention is.

[xlai (Olivia), 2016/06/30 14:42:31]

This metric measures the total time spent on encoding all the rows of an image
(jpeg or png), as part of canvas.toBlob API call, which occur during one or more
idle periods on the main thread. 

This metric is useful in helping us adjust the IdleTaskCompleteTimeoutDelay in
canvas.toBlob; when the encoding idle task is delayed for longer than
IdleTaskCompleteTimeoutDelay, browser will switch to non-idle task to force
encoding to happen on main thread.

[Ilya Sherman, 2016/06/30 17:22:37]

nit: s/as part of/as part of a
nit: s/call, which occur/call. Encoding occurs
nit: s/toBlob; when/toBlob. When
nit: s/browser will/the browser will
nit: s/switch to non-idle task/switch to a non-idle task
nit: s/on main thread/on the main thread

+  </summary>
+</histogram>
+
+<histogram name="Blink.Canvas.ToBlob.IdleTaskStatus" enum="IdleTaskStatus">
+  <owner>junov@chromium.org</owner>
+  <owner>xlai@chromium.org</owner>
+  <summary>
+    Records the status of the idle task when finishing a toBlob call.
+  </summary>
+</histogram>
+
+<histogram name="Blink.Canvas.ToBlob.InitiateEncodingDelay"
+    units="microseconds">
+  <owner>junov@chromium.org</owner>
+  <owner>xlai@chromium.org</owner>
+  <summary>Time elapsed from scheduling encoding to starting encoding.</summary>

[xlai (Olivia), 2016/06/30 14:42:31]

This metric measures the time spent from initiating image encoding
(jpeg or png) on idle task to the actual execution time of initiation, as part
of canvas.toBlob API call.

This metric is useful in helping us adjust the IdleTaskStartTimeoutDelay in
canvas.toBlob; when the initialization idle task is delayed for longer than
IdleTaskStartTimeoutDelay, browser will switch to non-idle task to force
initialization and encoding to occur on main thread.

[Ilya Sherman, 2016/06/30 17:22:37]

(similar nits here)

+</histogram>
+
+<histogram name="Blink.Canvas.ToBlobDuration" units="microseconds">
+  <owner>junov@chromium.org</owner>
+  <owner>xlai@chromium.org</owner>
+  <summary>Time spent on 2D canvas toBlob API call.</summary>
+</histogram>
+
 <histogram name="Blink.Canvas.ToDataURL" units="microseconds">
   <owner>junov@chromium.org</owner>
   <summary>Time spent on 2D canvas toDataURL API call.</summary>
@@ -78461,6 +78490,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </int>
 </enum>
 
+<enum name="IdleTaskStatus" type="int">
+  <int value="0" label="IdleTaskNotStarted"/>
+  <int value="1" label="IdleTaskStarted"/>
+  <int value="2" label="IdleTaskCompleted"/>
+  <int value="3" label="IdleTaskFailed"/>
+  <int value="4" label="IdleTaskSwitchedToMainThreadTask"/>
+  <int value="5" label="IdleTaskNotSupported"/>
+</enum>
+
 <enum name="IMECommitType" type="int">
   <obsolete>
     Deprecated 03/2015, and replaced by IMECommitType2.
@@ -93571,6 +93609,20 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Blink.Canvas.PutImageData"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="BlinkCanvasToBlobIdleEncodAndDelayType" separator=".">
+  <suffix name="JPEG"/>
+  <suffix name="PNG"/>
+  <affected-histogram name="Blink.Canvas.ToBlob.IdleEncodeDuration"/>
+  <affected-histogram name="Blink.Canvas.ToBlob.InitiateEncodingDelay"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="BlinkCanvasToBlobType" separator=".">
+  <suffix name="JPEG"/>
+  <suffix name="PNG"/>
+  <suffix name="WEBP"/>
+  <affected-histogram name="Blink.Canvas.ToBlobDuration"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="BlinkCanvasToDataURLTime" separator=".">
   <suffix name="BMP"/>
   <suffix name="GIF"/>