Find root scroll layer at tree activation

cc/picture_layer_impl.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/picture_layer_impl.h"
 
 #include "base/time.h"
 #include "cc/append_quads_data.h"
 #include "cc/checkerboard_draw_quad.h"
 #include "cc/debug_border_draw_quad.h"
@@ skipping 24 matching lines @@
 
 PictureLayerImpl::~PictureLayerImpl() {
 }
 
 const char* PictureLayerImpl::layerTypeAsString() const {
   return "PictureLayer";
 }
 
 void PictureLayerImpl::appendQuads(QuadSink& quadSink,
                                    AppendQuadsData& appendQuadsData) {
-
   const gfx::Rect& rect = visibleContentRect();
   gfx::Rect content_rect(gfx::Point(), contentBounds());
 
   SharedQuadState* sharedQuadState =
       quadSink.useSharedQuadState(createSharedQuadState());
   bool clipped = false;
   gfx::QuadF target_quad = MathUtil::mapQuad(
       drawTransform(),
       gfx::QuadF(rect),
       clipped);
@@ skipping 391 matching lines @@
     if (std::find(used_tilings.begin(), used_tilings.end(), tiling) ==
         used_tilings.end())
       to_remove.push_back(tiling);
   }
 
   for (size_t i = 0; i < to_remove.size(); ++i)
     tilings_.Remove(to_remove[i]);
 }
 
 }  // namespace cc