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 5b5d29e843231598da863f36a4d5c0a8304b907c..b5e72bcb08c2cc66b7449022543ab890645c6420 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -685,6 +685,7 @@ 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();
@@ -697,7 +698,7 @@ 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);