cc: Add some useful layer data to traces.

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/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/json/json_reader.h"
 #include "base/strings/stringprintf.h"
@@ skipping 1397 matching lines @@
       TRACE_DISABLED_BY_DEFAULT("cc.debug"),
       state,
       "cc::LayerImpl",
       LayerTypeAsString(),
       this);
   state->SetInteger("layer_id", id());
   state->BeginDictionary("bounds");
   MathUtil::AddToTracedValue(bounds_, state);
   state->EndDictionary();
 
+  state->SetDouble("opacity", opacity());
+
   state->BeginArray("position");
   MathUtil::AddToTracedValue(position_, state);
   state->EndArray();
 
   state->SetInteger("draws_content", DrawsContent());
   state->SetInteger("gpu_memory_usage", GPUMemoryUsageInBytes());
 
   state->BeginArray("scroll_offset");
   MathUtil::AddToTracedValue(scroll_offset_, state);
   state->EndArray();
@@ skipping 110 matching lines @@
 }
 
 void LayerImpl::NotifyAnimationFinished(
     base::TimeTicks monotonic_time,
     Animation::TargetProperty target_property) {
   if (target_property == Animation::ScrollOffset)
     layer_tree_impl_->InputScrollAnimationFinished();
 }
 
 }  // namespace cc