cc: Disable image hijack canvas when we don't have images in the map.

cc/playback/display_list_raster_source.cc

 // 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.
 
 #include "cc/playback/display_list_raster_source.h"
 
 #include <stddef.h>
 
 #include "base/containers/adapters.h"
 #include "base/strings/stringprintf.h"
@@ skipping 275 matching lines @@
 }
 
 void DisplayListRasterSource::PlaybackToCanvas(
     SkCanvas* raster_canvas,
     const gfx::Rect& canvas_bitmap_rect,
     const gfx::Rect& canvas_playback_rect,
     float contents_scale) const {
   PrepareForPlaybackToCanvas(raster_canvas, canvas_bitmap_rect,
                              canvas_playback_rect, contents_scale);
 
-  SkImageInfo info = raster_canvas->imageInfo();
-  ImageHijackCanvas canvas(info.width(), info.height(),
-                           image_decode_controller_);
-  canvas.addCanvas(raster_canvas);
-  RasterCommon(&canvas, NULL, canvas_bitmap_rect, canvas_playback_rect,
-               contents_scale);
+  if (display_list_->MayHaveDiscardableImages()) {
+    const SkImageInfo& info = raster_canvas->imageInfo();
+    ImageHijackCanvas canvas(info.width(), info.height(),
+                             image_decode_controller_);
+    canvas.addCanvas(raster_canvas);
+    RasterCommon(&canvas, nullptr, canvas_bitmap_rect, canvas_playback_rect,
+                 contents_scale);
+  } else {
+    RasterCommon(raster_canvas, nullptr, canvas_bitmap_rect,
+                 canvas_playback_rect, contents_scale);
+  }
 }
 
 void DisplayListRasterSource::PrepareForPlaybackToCanvas(
     SkCanvas* canvas,
     const gfx::Rect& canvas_bitmap_rect,
     const gfx::Rect& canvas_playback_rect,
     float contents_scale) const {
   // TODO(hendrikw): See if we can split this up into separate functions.
   bool partial_update = canvas_bitmap_rect != canvas_playback_rect;
 
@@ skipping 228 matching lines @@
     base::trace_event::MemoryAllocatorDump* dump =
         pmd->CreateAllocatorDump(dump_name);
     dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                     base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                     memory_usage);
   }
   return true;
 }
 
 }  // namespace cc