Implement convertToBlob() in OffscreenCanvas

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 178a267f26468c7b492235b1cf632cfe44d4cc1a..c20fcef5976d5927619942b0b05de73ae58f7454 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/CoreExport.h"
 #include "core/dom/DOMTypedArray.h"
 #include "core/fileapi/BlobCallback.h"
@@ -28,9 +29,9 @@ class CORE_EXPORT CanvasAsyncBlobCreator
       const IntSize&,
       BlobCallback*,
       double,
-      Document&);
-  void scheduleAsyncBlobCreation(bool canUseIdlePeriodScheduling,
-                                 const double& quality = 0.0);
+      Document*,
+      ScriptPromiseResolver*);
+  void scheduleAsyncBlobCreation(const double& quality);
   virtual ~CanvasAsyncBlobCreator();
   enum MimeType {
     MimeTypePng,
@@ -50,6 +51,13 @@ class CORE_EXPORT CanvasAsyncBlobCreator
                            // types
     IdleTaskCount,         // Should not be seen in production
   };
+
+  enum ToBlobFunctionType {
+    HTMLCanvasToBlobCallback,
+    OffscreenCanvasToBlobPromise,
+    NumberOfToBlobFunctionTypes
+  };
+
   // Methods are virtual for mocking in unit tests
   virtual void signalTaskSwitchInStartTimeoutEventForTesting() {}
   virtual void signalTaskSwitchInCompleteTimeoutEventForTesting() {}
@@ -62,7 +70,8 @@ class CORE_EXPORT CanvasAsyncBlobCreator
                          const IntSize&,
                          BlobCallback*,
                          double,
-                         Document&);
+                         Document*,
+                         ScriptPromiseResolver*);
   // Methods are virtual for unit testing
   virtual void scheduleInitiatePngEncoding();
   virtual void scheduleInitiateJpegEncoding(const double&);
@@ -94,12 +103,19 @@ class CORE_EXPORT CanvasAsyncBlobCreator
   const IntSize m_size;
   size_t m_pixelRowStride;
   const MimeType m_mimeType;
-  Member<BlobCallback> m_callback;
   double m_startTime;
   double m_scheduleInitiateStartTime;
   double m_elapsedTime;
+
+  ToBlobFunctionType m_functionType;
+
+  // Used for HTMLCanvasElement only
+  Member<BlobCallback> m_callback;
   Member<ParentFrameTaskRunners> m_parentFrameTaskRunner;
 
+  // Used for OffscreenCanvas only
+  Member<ScriptPromiseResolver> m_scriptPromiseResolver;
+
   // PNG
   bool initializePngStruct();
   void