UMA metrics for use count of wheel and touch scrolls.

cc/test/layer_tree_test.cc

Index: cc/test/layer_tree_test.cc
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index f5d9ee63ee551309de11dfc6e7045e38564d6695..f388cfc1373a67d0d51e77246e90c2288dfac64f 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -322,6 +322,9 @@ class LayerTreeHostClientForTesting : public LayerTreeHostClient,
                                      top_controls_delta);
   }
 
+  void RecordWheelAndTouchScrollingCount(bool has_scrolled_by_wheel,
+                                         bool has_scrolled_by_touch) override {}
+
   void RequestNewCompositorFrameSink() override {
     test_hooks_->RequestNewCompositorFrameSink();
   }