Add telemetry to track the time an event spent waiting for the main thread.

content/browser/renderer_host/input/immediate_input_router.cc

Index: content/browser/renderer_host/input/immediate_input_router.cc
diff --git a/content/browser/renderer_host/input/immediate_input_router.cc b/content/browser/renderer_host/input/immediate_input_router.cc
index 96e8bb9ac44dc6a81a71ab800d5ab60429ba28f8..277d433172dfbbd05e43f5b4e5949cb224dca9dd 100644
--- a/content/browser/renderer_host/input/immediate_input_router.cc
+++ b/content/browser/renderer_host/input/immediate_input_router.cc
@@ -479,7 +479,7 @@ void ImmediateInputRouter::ProcessInputEventAck(
   } else if (WebInputEvent::isTouchEventType(type)) {
     ProcessTouchAck(ack_result, latency_info);
   } else if (WebInputEvent::isGestureEventType(type)) {
-    ProcessGestureAck(type, ack_result);
+    ProcessGestureAck(type, ack_result, latency_info);
   }
 
   // WARNING: |this| may be deleted at this point.
@@ -541,11 +541,14 @@ void ImmediateInputRouter::ProcessWheelAck(InputEventAckState ack_result) {
   }
 }
 
-void ImmediateInputRouter::ProcessGestureAck(int type,
-                                             InputEventAckState ack_result) {
+void ImmediateInputRouter::ProcessGestureAck(
+    int type,
+    InputEventAckState ack_result,
+    const ui::LatencyInfo& latency_info) {
   const bool processed = (INPUT_EVENT_ACK_STATE_CONSUMED == ack_result);
-  client_->OnGestureEventAck(
-      gesture_event_filter_->GetGestureEventAwaitingAck(), ack_result);
+  client_->OnGestureEventAck(GestureEventWithLatencyInfo(
+          gesture_event_filter_->GetGestureEventAwaitingAck(), latency_info),
+      ack_result);
   gesture_event_filter_->ProcessGestureAck(processed, type);
 }