Track performance of toBlob and its complete timeout delay

third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h

Index: third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
index 64152fb3c0a5e14841d3073b9220150604079942..09fe0b26f6b6d6e65b04300a80c26e08163c597e 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
@@ -18,7 +18,7 @@ class JPEGImageEncoderState;
 
 class CORE_EXPORT CanvasAsyncBlobCreator : public GarbageCollectedFinalized<CanvasAsyncBlobCreator> {
 public:
-    static CanvasAsyncBlobCreator* create(DOMUint8ClampedArray* unpremultipliedRGBAImageData, const String& mimeType, const IntSize&, BlobCallback*);
+    static CanvasAsyncBlobCreator* create(DOMUint8ClampedArray* unpremultipliedRGBAImageData, const String& mimeType, const IntSize&, BlobCallback*, double);
     void scheduleAsyncBlobCreation(bool canUseIdlePeriodScheduling, const double& quality = 0.0);
     virtual ~CanvasAsyncBlobCreator();
     enum MimeType {
@@ -35,6 +35,12 @@ public:
         IdleTaskSwitchedToMainThreadTask,
         IdleTaskNotSupported // Idle tasks are not implemented for some image types
     };
+    // enum used histogram
+    enum IdleTaskTimeoutType {

[Justin Novosad, 2016/06/07 21:43:44]

I find these enum names a bit hard to interpret. We have basically four
categories of outcome: Failed, completed before idle task timeout, completed
after idle task timeout, completed without using idle scheduling (for webp).
each call to toBlob should add a count to exactly one of these bins.  "Failed"
could be expanded into more bins if we want to identify failure types.

+        IdleTaskStartTimeout,
+        IdleTaskCompleteTimeout,
+        IdleTaskTimeoutSupported
+    };
     // Methods are virtual for mocking in unit tests
     virtual void signalTaskSwitchInStartTimeoutEventForTesting() { }
     virtual void signalTaskSwitchInCompleteTimeoutEventForTesting() { }
@@ -45,7 +51,7 @@ public:
     }
 
 protected:
-    CanvasAsyncBlobCreator(DOMUint8ClampedArray* data, MimeType, const IntSize&, BlobCallback*);
+    CanvasAsyncBlobCreator(DOMUint8ClampedArray* data, MimeType, const IntSize&, BlobCallback*, double);
     // Methods are virtual for unit testing
     virtual void scheduleInitiatePngEncoding();
     virtual void scheduleInitiateJpegEncoding(const double&);
@@ -73,6 +79,8 @@ private:
     size_t m_pixelRowStride;
     const MimeType m_mimeType;
     CrossThreadPersistent<BlobCallback> m_callback;
+    double m_startTime;
+    void recordTimeoutSwitch(IdleTaskTimeoutType);
 
     // PNG
     bool initializePngStruct();
@@ -85,8 +93,8 @@ private:
     // WEBP
     void encodeImageOnEncoderThread(double quality);
 
-    void idleTaskStartTimeoutEvent(double quality);
-    void idleTaskCompleteTimeoutEvent();
+    void idleTaskStartTimeoutEvent(double quality, double startTime);
+    void idleTaskCompleteTimeoutEvent(double startTime);
 };
 
 } // namespace blink