Make OffscreenCanvas resizable

third_party/WebKit/Source/platform/graphics/CanvasSurfaceLayerBridge.cpp

 // Copyright 2016 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 "platform/graphics/CanvasSurfaceLayerBridge.h"
 
 #include "cc/layers/layer.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/layers/surface_layer.h"
 #include "cc/surfaces/sequence_surface_reference_factory.h"
@@ skipping 70 matching lines @@
   m_CCLayer->SetBackgroundColor(SK_ColorTRANSPARENT);
   m_webLayer = Platform::current()->compositorSupport()->createLayerFromCCLayer(
       m_CCLayer.get());
   GraphicsLayer::registerContentsLayer(m_webLayer.get());
 }
 
 void CanvasSurfaceLayerBridge::OnSurfaceCreated(const cc::SurfaceId& surfaceId,
                                                 int32_t width,
                                                 int32_t height,
                                                 float deviceScaleFactor) {
-  if (!m_currentSurfaceId.is_valid() && surfaceId.is_valid()) {
+  if (surfaceId.is_valid() && !m_currentSurfaceId.is_valid()) {
     m_currentSurfaceId = surfaceId;
     GraphicsLayer::unregisterContentsLayer(m_webLayer.get());
     m_webLayer->removeFromParent();
 
     scoped_refptr<cc::SurfaceLayer> surfaceLayer =
         cc::SurfaceLayer::Create(m_refFactory);
-    // TODO(xlai): Update this on resize.
     cc::SurfaceInfo info(surfaceId, deviceScaleFactor,
                          gfx::Size(width, height));
     surfaceLayer->SetSurfaceInfo(
         info, true /* scale layer bounds with surface size */);
     m_CCLayer = surfaceLayer;
 
     m_webLayer =
         Platform::current()->compositorSupport()->createLayerFromCCLayer(
             m_CCLayer.get());
     GraphicsLayer::registerContentsLayer(m_webLayer.get());
 
     m_observer->OnWebLayerReplaced();
+  } else if (m_currentSurfaceId != surfaceId) {
+    m_currentSurfaceId = surfaceId;
+    cc::SurfaceInfo info(m_currentSurfaceId, deviceScaleFactor,
+                         gfx::Size(width, height));
+    cc::SurfaceLayer* surfaceLayer =
+        static_cast<cc::SurfaceLayer*>(m_CCLayer.get());
+    surfaceLayer->SetSurfaceInfo(info, true);

[Fady Samuel, 2016/12/19 20:12:40]

I think you also need to update the layer bounds?
https://cs.chromium.org/chromium/src/content/renderer/child_frame_compositing...

[xlai (Olivia), 2016/12/19 22:30:15]

Although there is no visible effect seen at the moment, I agree that 
it is more correct to update layer bounds. 

+
+    m_observer->OnWebLayerReplaced();
   }
 }
 
 void CanvasSurfaceLayerBridge::satisfyCallback(
     const cc::SurfaceSequence& sequence) {
   m_service->Satisfy(sequence);
 }
 
 void CanvasSurfaceLayerBridge::requireCallback(
     const cc::SurfaceId& surfaceId,
     const cc::SurfaceSequence& sequence) {
   m_service->Require(surfaceId, sequence);
 }
 
 }  // namespace blink