Make OffscreenCanvas resizable

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index a6d00fdaf5c6e695a8977b6533c4f9a7d4597d81..dc8a76dc178b0b81543829883cb6943c9d723caa 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -1404,7 +1404,10 @@ void HTMLCanvasElement::createLayer() {
   m_surfaceLayerBridge->createSolidColorLayer();
 }
 
-void HTMLCanvasElement::OnWebLayerReplaced() {
+void HTMLCanvasElement::OnWebLayerReplaced(int width, int height) {
+  if (width != sourceWidth() || height != sourceHeight()) {
+    setSize(IntSize(width, height));
+  }
   setNeedsCompositingUpdate();
 }