Allow RecordingImageBufferSurface to prevent fallback.

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

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 935 matching lines @@
   CanvasMetrics::CountCanvasContextUsage(
       CanvasMetrics::kGPUAccelerated2DCanvasImageBufferCreated);
   return std::move(surface);
 }
 
 std::unique_ptr<ImageBufferSurface>
 HTMLCanvasElement::CreateUnacceleratedImageBufferSurface(
     OpacityMode opacity_mode) {
   if (ShouldUseDisplayList()) {
     auto surface = WTF::MakeUnique<RecordingImageBufferSurface>(
-        Size(), opacity_mode, context_->color_params());
+        Size(), RecordingImageBufferSurface::kAllowFallback, opacity_mode,

[pdr., 2017/04/25 23:00:27]

Should UnacceleratedImageBufferSurface also take an allow fallback parameter? Do
we need to allow fallback for the UnacceleratedImageBufferSurface surface
created a few lines below?

[Justin Novosad, 2017/04/26 14:25:25]

No, there is no fallback functionality in UnacceleratedImageBufferSurface

+        context_->color_params());
     if (surface->IsValid()) {
       CanvasMetrics::CountCanvasContextUsage(
           CanvasMetrics::kDisplayList2DCanvasImageBufferCreated);
       return std::move(surface);
     }
     // We fallback to a non-display-list surface without recording a metric
     // here.
   }
 
   auto surface = WTF::MakeUnique<UnacceleratedImageBufferSurface>(
@@ skipping 491 matching lines @@
     // Creates a placeholder layer first before Surface is created.
     surface_layer_bridge_->CreateSolidColorLayer();
   }
 }
 
 void HTMLCanvasElement::OnWebLayerReplaced() {
   SetNeedsCompositingUpdate();
 }
 
 }  // namespace blink