CC Animation: Use ElementId to attach CC animation players.

cc/test/fake_picture_layer_impl.cc

Index: cc/test/fake_picture_layer_impl.cc
diff --git a/cc/test/fake_picture_layer_impl.cc b/cc/test/fake_picture_layer_impl.cc
index 65297112fba8523cf1e11f2f2ed636b4a721272e..fd804b271cae737c41de7371f3c5bd78b27b3628 100644
--- a/cc/test/fake_picture_layer_impl.cc
+++ b/cc/test/fake_picture_layer_impl.cc
@@ -25,6 +25,7 @@ FakePictureLayerImpl::FakePictureLayerImpl(
       has_valid_tile_priorities_(false),
       use_set_valid_tile_priorities_flag_(false),
       release_resources_count_(0) {
+  SetElementId(NextElementId());
   SetBounds(raster_source->GetSize());
   SetRasterSourceOnPending(raster_source, Region());
 }
@@ -41,6 +42,7 @@ FakePictureLayerImpl::FakePictureLayerImpl(
       has_valid_tile_priorities_(false),
       use_set_valid_tile_priorities_flag_(false),
       release_resources_count_(0) {
+  SetElementId(NextElementId());
   SetBounds(layer_bounds);
   SetRasterSourceOnPending(raster_source, Region());
 }
@@ -53,7 +55,9 @@ FakePictureLayerImpl::FakePictureLayerImpl(LayerTreeImpl* tree_impl,
       did_become_active_call_count_(0),
       has_valid_tile_priorities_(false),
       use_set_valid_tile_priorities_flag_(false),
-      release_resources_count_(0) {}
+      release_resources_count_(0) {
+  SetElementId(NextElementId());
+}
 
 std::unique_ptr<LayerImpl> FakePictureLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {