Add Layer Id information to the LayerTree json string

cc/layers/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/layers/layer_impl.h"
 
 #include "base/json/json_reader.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ skipping 638 matching lines @@
   //
   gfx::Vector2dF delta_from_pinch =
       gfx::Rect(scroll_clip_layer_->bounds()).bottom_right() - gfx::PointF();
   delta_from_pinch.Scale((1.f - scale_delta) / (scale * scale_delta));
 
   return delta_from_scroll + delta_from_pinch;
 }
 
 base::DictionaryValue* LayerImpl::LayerTreeAsJson() const {
   base::DictionaryValue* result = new base::DictionaryValue;
+  result->SetInteger("LayerId", id());
   result->SetString("LayerType", LayerTypeAsString());
 
   base::ListValue* list = new base::ListValue;
   list->AppendInteger(bounds().width());
   list->AppendInteger(bounds().height());
   result->Set("Bounds", list);
 
   list = new base::ListValue;
   list->AppendDouble(position_.x());
   list->AppendDouble(position_.y());
@@ skipping 966 matching lines @@
   gfx::Transform scaled_draw_transform =
       draw_properties_.target_space_transform;
   scaled_draw_transform.Scale(SK_MScalar1 / scale, SK_MScalar1 / scale);
   gfx::Size scaled_content_bounds =
       gfx::ToCeiledSize(gfx::ScaleSize(content_bounds(), scale));
   return MathUtil::MapEnclosingClippedRect(scaled_draw_transform,
                                            gfx::Rect(scaled_content_bounds));
 }
 
 }  // namespace cc