Rename cc::ResourceProvider::ResourceId to cc::ResourceId and move it to its own file.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 54776e77315b74a08c74c23351547aeb77b6bc73..91e0ce12d92757e309f2cdaf5b52d9bcb9a418fa 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -470,13 +470,12 @@ class CC_EXPORT LayerTreeHostImpl
   void EvictAllUIResources();
   bool EvictedUIResourcesExist() const;
 
-  virtual ResourceProvider::ResourceId ResourceIdForUIResource(
-      UIResourceId uid) const;
+  virtual ResourceId ResourceIdForUIResource(UIResourceId uid) const;
 
   virtual bool IsUIResourceOpaque(UIResourceId uid) const;
 
   struct UIResourceData {
-    ResourceProvider::ResourceId resource_id;
+    ResourceId resource_id;
     gfx::Size size;
     bool opaque;
   };