Prepare for including compositing reasons in GraphicsLayerDebugInfo

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/json/json_reader.h"
 #include "base/strings/stringprintf.h"
 #include "cc/animation/animation_registrar.h"
@@ skipping 1363 matching lines @@
     gfx::BoxF box(bounds().width(), bounds().height(), 0.f);
     gfx::BoxF inflated;
     if (layer_animation_controller_->AnimatedBoundsForBox(box, &inflated))
       state->Set("animated_bounds", MathUtil::AsValue(inflated).release());
   }
 
   if (debug_info_.get()) {
     std::string str;
     debug_info_->AppendAsTraceFormat(&str);
     base::JSONReader json_reader;
-    // Parsing the JSON and re-encoding it is not very efficient,
-    // but it's the simplest way to achieve the desired effect, which
-    // is to output:
-    // {..., layout_rects: [{geometry_rect: ...}, ...], ...}
-    // rather than:
-    // {layout_rects: "[{geometry_rect: ...}, ...]", ...}
-    state->Set("layout_rects", json_reader.ReadToValue(str));
+    scoped_ptr<base::Value> debug_info_value(json_reader.ReadToValue(str));
+
+    // TODO(vollick): The TYPE_LIST code below is brittle; it assumes the only
+    // debug info is the layout rects. In future, this will be generalized, and
+    // debug info will return a dictionary to be merged into state. Until then,
+    // we unfortunately have to support both situations. Once we've migrated,
+    // the TYPE_LIST branch will be deleted.
+    if (debug_info_value->IsType(base::Value::TYPE_LIST)) {
+      // Parsing the JSON and re-encoding it is not very efficient,
+      // but it's the simplest way to achieve the desired effect, which
+      // is to output:
+      // {..., layout_rects: [{geometry_rect: ...}, ...], ...}
+      // rather than:
+      // {layout_rects: "[{geometry_rect: ...}, ...]", ...}
+      state->Set("layout_rects", debug_info_value.release());
+    } else if (debug_info_value->IsType(base::Value::TYPE_DICTIONARY)) {
+      base::DictionaryValue* dictionary_value = NULL;
+      bool converted_to_dictionary =
+          debug_info_value->GetAsDictionary(&dictionary_value);
+      DCHECK(converted_to_dictionary);
+      state->MergeDictionary(dictionary_value);
+    } else {
+      NOTREACHED();
+    }
   }
 }
 
 size_t LayerImpl::GPUMemoryUsageInBytes() const { return 0; }
 
 scoped_ptr<base::Value> LayerImpl::AsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   AsValueInto(state.get());
   return state.PassAs<base::Value>();
 }
 
 void LayerImpl::RunMicroBenchmark(MicroBenchmarkImpl* benchmark) {
   benchmark->RunOnLayer(this);
 }
 
 }  // namespace cc