cc: Add tile-free software compositing mode.

cc/resources/tile_manager.cc

 // Copyright 2012 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/resources/tile_manager.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "cc/debug/debug_colors.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/resources/raster_worker_pool.h"
 #include "cc/resources/resource_pool.h"
 #include "cc/resources/tile.h"
 #include "third_party/skia/include/core/SkDevice.h"
 
 namespace cc {
 
 namespace {
@@ skipping 876 matching lines @@
 
   if (analysis->is_solid_color)
     return;
 
   SkBitmap bitmap;
   bitmap.setConfig(SkBitmap::kARGB_8888_Config, rect.width(), rect.height());
   bitmap.setPixels(buffer);
   SkDevice device(bitmap);
   SkCanvas canvas(&device);
 
+#ifndef NDEBUG
+  // Any non-painted areas will be left in this color.
+  canvas.clear(DebugColors::NonPaintedFillColor());
+#endif  // NDEBUG
+
   if (stats_instrumentation->record_rendering_stats()) {
     PicturePileImpl::RasterStats raster_stats;
     picture_pile->Raster(&canvas, rect, contents_scale, &raster_stats);
     stats_instrumentation->AddRaster(
         raster_stats.total_rasterize_time,
         raster_stats.best_rasterize_time,
         raster_stats.total_pixels_rasterized,
         metadata.is_tile_in_pending_tree_now_bin);
 
     HISTOGRAM_CUSTOM_COUNTS(
@@ skipping 46 matching lines @@
                     is_predicted_solid && predicted_color != actual_color);
   HISTOGRAM_BOOLEAN("Renderer4.ColorPredictor.Accuracy",
                     is_predicted_solid == is_actually_solid &&
                     (!is_predicted_solid || predicted_color == actual_color));
   HISTOGRAM_BOOLEAN("Renderer4.ColorPredictor.IsCorrectSolid",
                     is_predicted_solid == is_actually_solid &&
                     (is_predicted_solid && predicted_color == actual_color));
 }
 
 }  // namespace cc