Have CanvasAsyncBlobCreator speculative idle tasks keep a weak 'this'.

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

Index: third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
index 007947c366e67c3bd4d36e2f8cf99ac28c9aa18f..a917430d263822706ba8eb916a46465db16dfaa2 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
@@ -127,7 +127,7 @@ void CanvasAsyncBlobCreator::scheduleAsyncBlobCreation(bool canUseIdlePeriodSche
 
 void CanvasAsyncBlobCreator::scheduleInitiateJpegEncoding(const double& quality)
 {
-    Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::initiateJpegEncoding, this, quality));
+    Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::initiateJpegEncoding, WeakPersistentThisPointer<CanvasAsyncBlobCreator>(this), quality));
 }
 
 void CanvasAsyncBlobCreator::initiateJpegEncoding(const double& quality, double deadlineSeconds)
@@ -149,7 +149,7 @@ void CanvasAsyncBlobCreator::initiateJpegEncoding(const double& quality, double
 
 void CanvasAsyncBlobCreator::scheduleInitiatePngEncoding()
 {
-    Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::initiatePngEncoding, this));
+    Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::initiatePngEncoding, WeakPersistentThisPointer<CanvasAsyncBlobCreator>(this)));
 }
 
 void CanvasAsyncBlobCreator::initiatePngEncoding(double deadlineSeconds)