Use the solid color detection to create solid layers

cc/resources/picture_pile.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/picture_pile.h"
 
 #include <algorithm>
 #include <limits>
 #include <vector>
 
@@ skipping 131 matching lines @@
   }
 
   *record_rects = vertical_clustering;
   return vertical_density;
 }
 
 }  // namespace
 
 namespace cc {
 
-PicturePile::PicturePile()
-    : is_suitable_for_gpu_rasterization_(true),
-      is_solid_color_(true),
-      solid_color_(SK_ColorTRANSPARENT) {
+PicturePile::PicturePile() : is_suitable_for_gpu_rasterization_(true) {
 }
 
 PicturePile::~PicturePile() {
 }
 
 bool PicturePile::UpdateAndExpandInvalidation(
     ContentLayerClient* painter,
     Region* invalidation,
     SkColor background_color,
     bool contents_opaque,
@@ skipping 391 matching lines @@
     if (it->second.GetPicture() != picture)
       return;
   }
   skia::AnalysisCanvas canvas(recorded_viewport_.width(),
                               recorded_viewport_.height());
   picture->Raster(&canvas, NULL, Region(), 1.0f);
   is_solid_color_ = canvas.GetColorIfSolid(&solid_color_);
 }
 
 }  // namespace cc