Disallow resizing on OffscreenCanvas that has been transferred control from canvas

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/offscreencanvas/OffscreenCanvas.h"
 
 #include "core/dom/ExceptionCode.h"
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/graphics/OffscreenCanvasFrameDispatcherImpl.h"
 #include "wtf/MathExtras.h"
 #include <memory>
 
 namespace blink {
 
 OffscreenCanvas::OffscreenCanvas(const IntSize& size)
     : m_size(size)
     , m_originClean(true)
 {
 }
 
 OffscreenCanvas* OffscreenCanvas::create(unsigned width, unsigned height)
 {
     return new OffscreenCanvas(IntSize(clampTo<int>(width), clampTo<int>(height)));
 }
 
-void OffscreenCanvas::setWidth(unsigned width)
+void OffscreenCanvas::setWidth(unsigned width, ExceptionState& exceptionState)
 {
     // If this OffscreenCanvas is transferred control by an html canvas,
     // its size is determined by html canvas's size and cannot be resized.
-    if (m_canvasId >= 0)
+    if (m_canvasId >= 0) {
+        exceptionState.throwDOMException(InvalidStateError, "Resizing is not allowed on an OffscreenCanvas that has been transferred control from a canvas.");
         return;
+    }
     m_size.setWidth(clampTo<int>(width));
 }
 
-void OffscreenCanvas::setHeight(unsigned height)
+void OffscreenCanvas::setHeight(unsigned height, ExceptionState& exceptionState)
 {
     // Same comment as above.
-    if (m_canvasId >= 0)
+    if (m_canvasId >= 0) {
+        exceptionState.throwDOMException(InvalidStateError, "Resizing is not allowed on an OffscreenCanvas that has been transferred control from a canvas.");
         return;
+    }
     m_size.setHeight(clampTo<int>(height));
 }
 
 void OffscreenCanvas::setNeutered()
 {
     ASSERT(!m_context);
     m_isNeutered = true;
     m_size.setWidth(0);
     m_size.setHeight(0);
 }
@@ skipping 99 matching lines @@
     }
     return m_frameDispatcher.get();
 }
 
 DEFINE_TRACE(OffscreenCanvas)
 {
     visitor->trace(m_context);
 }
 
 } // namespace blink