Track performance of toBlob and its complete timeout delay

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index ceebfd501035a0a9f250aa662cfd7ee32b70fdf8..732afbfb0bd2abcb854b8e11af51b705c642f550 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -665,6 +665,7 @@ void HTMLCanvasElement::toBlob(BlobCallback* callback, const String& mimeType, c
         return;
     }
 
+    double startTime = WTF::monotonicallyIncreasingTime();
     double quality = UndefinedQualityValue;
     if (!qualityArgument.isEmpty()) {
         v8::Local<v8::Value> v8Value = qualityArgument.v8Value();
@@ -677,7 +678,7 @@ void HTMLCanvasElement::toBlob(BlobCallback* callback, const String& mimeType, c
 
     ImageData* imageData = toImageData(BackBuffer, SnapshotReasonToBlob);
 
-    CanvasAsyncBlobCreator* asyncCreator = CanvasAsyncBlobCreator::create(imageData->data(), encodingMimeType, imageData->size(), callback);
+    CanvasAsyncBlobCreator* asyncCreator = CanvasAsyncBlobCreator::create(imageData->data(), encodingMimeType, imageData->size(), callback, startTime);
 
     bool useIdlePeriodScheduling = (encodingMimeType != "image/webp");
     asyncCreator->scheduleAsyncBlobCreation(useIdlePeriodScheduling, quality);