Revert of Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo.

cc/layers/layer_client.h

Index: cc/layers/layer_client.h
diff --git a/cc/layers/layer_client.h b/cc/layers/layer_client.h
index 524399d0d84e5e72379b80338c87dbc1213e4c16..bcdf1c3c77d7124d5b82c9daec769ec7c37d7c28 100644
--- a/cc/layers/layer_client.h
+++ b/cc/layers/layer_client.h
@@ -4,6 +4,8 @@
 
 #ifndef CC_LAYERS_LAYER_CLIENT_H_
 #define CC_LAYERS_LAYER_CLIENT_H_
+
+#include <string>
 
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
@@ -16,19 +18,14 @@
 
 namespace cc {
 
-class Layer;
-
 class CC_EXPORT LayerClient {
  public:
   // Returns a pointer to a debug info object, if one has been computed.
   // If not, returns nullptr.
   // If the returned pointer is non-nullptr, the caller takes
   // ownership of the pointer.
-  //
-  // A pointer to the layer is provided for the convenience of layer clients
-  // which service multiple layers.
   virtual scoped_refptr<base::trace_event::ConvertableToTraceFormat>
-  TakeDebugInfo(Layer* layer) = 0;
+      TakeDebugInfo() = 0;
 
  protected:
   virtual ~LayerClient() {}