publish canvas context API stat metrics

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 9d6c163acca5807d32a8c319d7c52d73e7822f0c..364ea2a43baedf48d215618c876e1e1928841882 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -51281,6 +51281,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WebCore.CanvasContextStat" enum="CanvasContextStat">
+  <owner>zmin@chromium.org</owner>
+  <summary>The State of Canvas 2D Context API.</summary>
+</histogram>
+
 <histogram name="WebCore.DistillabilityUs" units="microseconds">
   <owner>wychen@chromium.org</owner>
   <summary>
@@ -55448,6 +55453,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="4" label="CACHE_MISS"/>
 </enum>
 
+<enum name="CanvasContextStat" type="int">
+  <int value="0" label="ContextsCreated"/>

[Justin Novosad, 2015/11/19 20:36:09]

update names based on earlier comments.

[zmin, 2015/11/19 22:23:36]

Done.

+  <int value="1" label="ContextsCreatedWithGPUAccelerated"/>
+  <int value="2" label="ContextsCreatedWithDisplayList"/>
+  <int value="3" label="ContextsCreatedWithSoftware"/>
+  <int value="4" label="GPUContextLost"/>
+  <int value="5" label="SoftwareContextCreationFailed"/>
+  <int value="6" label="GPUContextCreationFailed"/>
+  <int value="7" label="DisplayListFallbackToRaster"/>
+</enum>
+
 <enum name="CanvasContextType" type="int">
   <int value="0" label="2d"/>
   <int value="1" label="webkit-3d"/>