Add UMA metric for tracking listeners for blocking touch while fling is happening

content/renderer/input/input_handler_wrapper.cc

Index: content/renderer/input/input_handler_wrapper.cc
diff --git a/content/renderer/input/input_handler_wrapper.cc b/content/renderer/input/input_handler_wrapper.cc
index c8280e4a3164d0c0084b3450a9ae177d3d1c79d4..e51adf5fdcf55dd1decd8012f1498c9dc54e1e80 100644
--- a/content/renderer/input/input_handler_wrapper.cc
+++ b/content/renderer/input/input_handler_wrapper.cc
@@ -51,6 +51,7 @@ blink::WebGestureCurve* InputHandlerWrapper::CreateFlingAnimationCurve(
     blink::WebGestureDevice deviceSource,
     const blink::WebFloatPoint& velocity,
     const blink::WebSize& cumulative_scroll) {
+  input_handler_manager_->DidStartFlinging(true);
   return blink::Platform::current()->createFlingAnimationCurve(
       deviceSource, velocity, cumulative_scroll);
 }
@@ -76,4 +77,8 @@ void InputHandlerWrapper::DidAnimateForInput() {
   input_handler_manager_->DidAnimateForInput();
 }
 
+void InputHandlerWrapper::DidStartFlinging(bool is_on_impl) {
+  input_handler_manager_->DidStartFlinging(is_on_impl);
+}
+
 }  // namespace content