Minor clean up in transferToImageBitmap API

The transferToImageBitmap is an API in OffscreenCanvas. This API could
throw exception in certain cases, which means that the
OffscreenCanvas::transferToImageBitmap() method has a ExceptionState&
parameter.

In our current implementation, we do all the exception check in the above
method. However, we still pass the ExceptionState& parameter to the
CanvasRenderingContext::transferToImageBitmap() method, and this method
is overriden by OffscreenCanvasRenderingContext2D, WebGLRenderingContext,
and WebGL2RenderingContext. So this method in all these sub-classes also
take a ExceptionState& parameter but do nothing with it. We should not
need to pass this parameter to CanvasRenderingContext::transferToImageBitmap.

TBR=kbr@chromium.org, zmo@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2440213003
Cr-Commit-Position: refs/heads/master@{#427188}

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h

@@ -165,9 +165,7 @@ class CORE_EXPORT CanvasRenderingContext
 
   // OffscreenCanvas-specific methods
   OffscreenCanvas* getOffscreenCanvas() const { return m_offscreenCanvas; }
-  virtual ImageBitmap* transferToImageBitmap(ExceptionState&) {
-    return nullptr;
-  }
+  virtual ImageBitmap* transferToImageBitmap() { return nullptr; }
 
   bool wouldTaintOrigin(CanvasImageSource*, SecurityOrigin* = nullptr);
   void didMoveToNewDocument(Document*);

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp

@@ -76,7 +76,7 @@ ImageBitmap* OffscreenCanvas::transferToImageBitmap(
                                      "OffscreenCanvas with no context");
     return nullptr;
   }
-  ImageBitmap* image = m_context->transferToImageBitmap(exceptionState);
+  ImageBitmap* image = m_context->transferToImageBitmap();
   if (!image) {
     // Undocumented exception (not in spec)
     exceptionState.throwDOMException(V8Error, "Out of memory");

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

@@ -137,8 +137,7 @@ OffscreenCanvasRenderingContext2D::transferToStaticBitmapImage() {
   return image;
 }
 
-ImageBitmap* OffscreenCanvasRenderingContext2D::transferToImageBitmap(
-    ExceptionState& exceptionState) {
+ImageBitmap* OffscreenCanvasRenderingContext2D::transferToImageBitmap() {
   RefPtr<StaticBitmapImage> image = transferToStaticBitmapImage();
   if (!image)
     return nullptr;

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h

@@ -82,7 +82,7 @@ class MODULES_EXPORT OffscreenCanvasRenderingContext2D final
   bool hasAlpha() const final { return creationAttributes().alpha(); }
   bool isContextLost() const override;
 
-  ImageBitmap* transferToImageBitmap(ExceptionState&) final;
+  ImageBitmap* transferToImageBitmap() final;
 
  protected:
   OffscreenCanvasRenderingContext2D(

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.cpp

@@ -102,8 +102,7 @@ void WebGL2RenderingContext::setOffscreenCanvasGetContextResult(
   result.setWebGL2RenderingContext(this);
 }
 
-ImageBitmap* WebGL2RenderingContext::transferToImageBitmap(
-    ExceptionState& exceptionState) {
+ImageBitmap* WebGL2RenderingContext::transferToImageBitmap() {
   NOTIMPLEMENTED();
   return nullptr;
 }

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h

@@ -39,7 +39,7 @@ class WebGL2RenderingContext : public WebGL2RenderingContextBase {
   CanvasRenderingContext::ContextType getContextType() const override {
     return CanvasRenderingContext::ContextWebgl2;
   }
-  ImageBitmap* transferToImageBitmap(ExceptionState&) final;
+  ImageBitmap* transferToImageBitmap() final;
   String contextName() const override { return "WebGL2RenderingContext"; }
   void registerContextExtensions() override;
   void setCanvasGetContextResult(RenderingContext&) final;

third_party/WebKit/Source/modules/webgl/WebGLRenderingContext.cpp

@@ -163,8 +163,7 @@ void WebGLRenderingContext::setOffscreenCanvasGetContextResult(
   result.setWebGLRenderingContext(this);
 }
 
-ImageBitmap* WebGLRenderingContext::transferToImageBitmap(
-    ExceptionState& exceptionState) {
+ImageBitmap* WebGLRenderingContext::transferToImageBitmap() {
   return transferToImageBitmapBase();
 }
 

third_party/WebKit/Source/modules/webgl/WebGLRenderingContext.h

@@ -63,7 +63,7 @@ class WebGLRenderingContext final : public WebGLRenderingContextBase {
   CanvasRenderingContext::ContextType getContextType() const override {
     return CanvasRenderingContext::ContextWebgl;
   }
-  ImageBitmap* transferToImageBitmap(ExceptionState&) final;
+  ImageBitmap* transferToImageBitmap() final;
   String contextName() const override { return "WebGLRenderingContext"; }
   void registerContextExtensions() override;
   void setCanvasGetContextResult(RenderingContext&) final;