Added LayerTreeHostImpl::layerTreeAsJson which serializes a layer tree

cc/nine_patch_layer_impl.h

Index: cc/nine_patch_layer_impl.h
diff --git a/cc/nine_patch_layer_impl.h b/cc/nine_patch_layer_impl.h
index f574c3a6875f2c16f415c10d238848f772ac7276..3201e1991a39193741b7442ddc479bb2861fe538 100644
--- a/cc/nine_patch_layer_impl.h
+++ b/cc/nine_patch_layer_impl.h
@@ -11,6 +11,10 @@
 #include "ui/gfx/size.h"
 #include "ui/gfx/rect.h"
 
+namespace base {
+class DictionaryValue;
+}
+
 namespace cc {
 
 class CC_EXPORT NinePatchLayerImpl : public LayerImpl {
@@ -31,6 +35,8 @@ public:
     virtual void dumpLayerProperties(std::string*, int indent) const OVERRIDE;
     virtual void didLoseOutputSurface() OVERRIDE;
 
+    virtual base::DictionaryValue* layerTreeAsJson() const OVERRIDE;
+
 protected:
     explicit NinePatchLayerImpl(int id);