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

content/renderer/gpu/input_event_filter.cc

Index: content/renderer/gpu/input_event_filter.cc
diff --git a/content/renderer/gpu/input_event_filter.cc b/content/renderer/gpu/input_event_filter.cc
index 0db5814b2c0ab767d334bfb7b0a8cd556b1a00cc..95de92ca252082bd71437f7e9aa610820f99085c 100644
--- a/content/renderer/gpu/input_event_filter.cc
+++ b/content/renderer/gpu/input_event_filter.cc
@@ -7,6 +7,7 @@
 #include "base/debug/trace_event.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/metrics/histogram.h"
 #include "content/common/input_messages.h"
 #include "content/common/view_messages.h"
 #include "content/public/common/content_switches.h"
@@ -106,7 +107,8 @@ bool InputEventFilter::OnMessageReceived(const IPC::Message& message) {
 // static
 const WebInputEvent* InputEventFilter::CrackMessage(
     const IPC::Message& message,
-    ui::LatencyInfo* latency_info) {
+    ui::LatencyInfo* latency_info,
+    bool* is_keyboard_shortcut) {
   DCHECK(message.type() == InputMsg_HandleInputEvent::ID);
 
   PickleIterator iter(message);
@@ -114,6 +116,8 @@ const WebInputEvent* InputEventFilter::CrackMessage(
   IPC::ParamTraits<IPC::WebInputEventPointer>::Read(&message, &iter, &event);
   if (latency_info)
     IPC::ParamTraits<ui::LatencyInfo>::Read(&message, &iter, latency_info);
+  if (is_keyboard_shortcut)
+    IPC::ParamTraits<bool>::Read(&message, &iter, is_keyboard_shortcut);
   return event;
 }
 
@@ -121,7 +125,21 @@ InputEventFilter::~InputEventFilter() {
 }
 
 void InputEventFilter::ForwardToMainListener(const IPC::Message& message) {
-  main_listener_->OnMessageReceived(message);
+  if (message.type() != InputMsg_HandleInputEvent::ID) {
+    main_listener_->OnMessageReceived(message);
+    return;
+  }
+  ui::LatencyInfo latency_info;
+  bool is_keyboard_shortcut;
+  const WebInputEvent* event = CrackMessage(message, &latency_info,
+      &is_keyboard_shortcut);
+
+  latency_info.AddLatencyNumber(
+      ui::INPUT_EVENT_LATENCY_RECEIVED_ON_MAIN_THREAD_COMPONENT,
+      message.routing_id(), 0);
+
+  main_listener_->OnMessageReceived(InputMsg_HandleInputEvent(
+      message.routing_id(), event, latency_info, is_keyboard_shortcut));
 }
 
 void InputEventFilter::ForwardToHandler(const IPC::Message& message) {
@@ -137,17 +155,23 @@ void InputEventFilter::ForwardToHandler(const IPC::Message& message) {
   }
 
   ui::LatencyInfo latency_info;
-  const WebInputEvent* event = CrackMessage(message, &latency_info);
+  bool is_keyboard_shortcut;
+  const WebInputEvent* event = CrackMessage(message, &latency_info,
+      &is_keyboard_shortcut);
 
   InputEventAckState ack =
       handler_.Run(message.routing_id(), event, latency_info);
 
   if (ack == INPUT_EVENT_ACK_STATE_NOT_CONSUMED) {
     TRACE_EVENT0("input", "InputEventFilter::ForwardToHandler");
+    latency_info.AddLatencyNumber(
+        ui::INPUT_EVENT_LATENCY_SENT_FROM_IMPL_THREAD_COMPONENT,
+        message.routing_id(), 0);
     main_loop_->PostTask(
         FROM_HERE,
         base::Bind(&InputEventFilter::ForwardToMainListener,
-                   this, message));
+                   this, InputMsg_HandleInputEvent(message.routing_id(), event,
+                       latency_info, is_keyboard_shortcut)));
     return;
   }
 
@@ -163,7 +187,7 @@ void InputEventFilter::SendACK(const IPC::Message& message,
       base::Bind(&InputEventFilter::SendMessageOnIOThread, this,
                  InputHostMsg_HandleInputEvent_ACK(
                      message.routing_id(),
-                     CrackMessage(message, NULL)->type,
+                     CrackMessage(message, NULL, NULL)->type,
                      ack_result)));
 }