Synchronize OffscreenCanvas content with the placeholder canvas

third_party/WebKit/Source/platform/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
 import("//third_party/WebKit/Source/config.gni")
@@ skipping 818 matching lines @@
     "graphics/InterceptingCanvas.cpp",
     "graphics/InterceptingCanvas.h",
     "graphics/LinkHighlight.h",
     "graphics/LoggingCanvas.cpp",
     "graphics/LoggingCanvas.h",
     "graphics/MailboxTextureHolder.cpp",
     "graphics/MailboxTextureHolder.h",
     "graphics/OffscreenCanvasFrameDispatcher.h",
     "graphics/OffscreenCanvasFrameDispatcherImpl.cpp",
     "graphics/OffscreenCanvasFrameDispatcherImpl.h",
+    "graphics/OffscreenCanvasPlaceholder.cpp",
+    "graphics/OffscreenCanvasPlaceholder.h",
     "graphics/PaintGeneratedImage.cpp",
     "graphics/PaintGeneratedImage.h",
     "graphics/PaintInvalidationReason.cpp",
     "graphics/PaintInvalidationReason.h",
     "graphics/Path.cpp",
     "graphics/Path.h",
     "graphics/PathTraversalState.cpp",
     "graphics/PathTraversalState.h",
     "graphics/Pattern.cpp",
     "graphics/Pattern.h",
@@ skipping 1153 matching lines @@
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//cc/surfaces:surface_id",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }