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

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 11014402c8f7cd8ac8d9091220c08194e5eb81db..5c936220cfff34d2d336a24f9fb102070dab8db2 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -746,9 +746,8 @@ gfx::Size PictureLayerImpl::CalculateTileSize(
   return gfx::Size(tile_width, tile_height);
 }
 
-void PictureLayerImpl::GetContentsResourceId(
-    ResourceProvider::ResourceId* resource_id,
-    gfx::Size* resource_size) const {
+void PictureLayerImpl::GetContentsResourceId(ResourceId* resource_id,
+                                             gfx::Size* resource_size) const {
   // The bounds and the pile size may differ if the pile wasn't updated (ie.
   // PictureLayer::Update didn't happen). In that case the pile will be empty.
   DCHECK_IMPLIES(!raster_source_->GetSize().IsEmpty(),