Revert of Simplify CanvasAsyncBlobCreator by removing ContextObserver and related tests

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 0a714c7002f366c818430f0f8bd78ac9cb854c6a..df7f1d787ee125dfa55e9135f2ee1bb74509d8fc 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
@@ -4,6 +4,7 @@
 
 #include "core/CoreExport.h"
 #include "core/dom/DOMTypedArray.h"
+#include "core/dom/ExecutionContext.h"
 #include "core/fileapi/BlobCallback.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/heap/Handle.h"
@@ -19,15 +20,19 @@
 class CORE_EXPORT CanvasAsyncBlobCreator
     : public RefCounted<CanvasAsyncBlobCreator> {
 public:
-    static PassRefPtr<CanvasAsyncBlobCreator> create(PassRefPtr<DOMUint8ClampedArray> unpremultipliedRGBAImageData, const String& mimeType, const IntSize&, BlobCallback*);
+    static PassRefPtr<CanvasAsyncBlobCreator> create(PassRefPtr<DOMUint8ClampedArray> unpremultipliedRGBAImageData, const String& mimeType, const IntSize&, BlobCallback*, ExecutionContext*);
     void scheduleAsyncBlobCreation(bool canUseIdlePeriodScheduling, double quality = 0.0);
     virtual ~CanvasAsyncBlobCreator();
 
+protected:
+    CanvasAsyncBlobCreator(PassRefPtr<DOMUint8ClampedArray> data, const String& mimeType, const IntSize&, BlobCallback*);
+    virtual void scheduleCreateBlobAndCallOnMainThread();
+    virtual void scheduleCreateNullptrAndCallOnMainThread();
+    virtual void scheduleClearSelfRefOnMainThread();
+    std::atomic<bool> m_cancelled;
+
 private:
-    CanvasAsyncBlobCreator(PassRefPtr<DOMUint8ClampedArray> data, const String& mimeType, const IntSize&, BlobCallback*);
-    void scheduleCreateBlobAndCallOnMainThread();
-    void scheduleCreateNullptrAndCallOnMainThread();
-    void scheduleClearSelfRefOnMainThread();
+    friend class CanvasAsyncBlobCreatorTest;
 
     OwnPtr<PNGImageEncoderState> m_encoderState;
     RefPtr<DOMUint8ClampedArray> m_data;
@@ -49,6 +54,13 @@
     void createBlobAndCall();
 
     void encodeImageOnEncoderThread(double quality);
+    bool initializeEncodeImageOnEncoderThread();
+    void nonprogressiveEncodeImageOnEncoderThread(double quality);
+    void progressiveEncodeImageOnEncoderThread();
+
+    class ContextObserver;
+    void createContextObserver(ExecutionContext*);
+    OwnPtrWillBePersistent<ContextObserver> m_contextObserver;
 };
 
 } // namespace blink