Add UMA histograms for more detailed latency tracking on the CRD host.

remoting/protocol/host_event_dispatcher.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef REMOTING_PROTOCOL_HOST_EVENT_DISPATCHER_H_
 #define REMOTING_PROTOCOL_HOST_EVENT_DISPATCHER_H_
 
 #include "remoting/protocol/channel_dispatcher_base.h"
 #include "remoting/protocol/protobuf_message_parser.h"
 
 namespace remoting {
 namespace protocol {
 
 class EventMessage;
 class InputStub;
 
 // HostEventDispatcher dispatches incoming messages on the event
 // channel to InputStub.
 class HostEventDispatcher : public ChannelDispatcherBase {
  public:
-  typedef base::Callback<void(int64)> EventTimestampCallback;
+  typedef base::Callback<void(int64_t)> OnInputEventCallback;
 
   HostEventDispatcher();
   ~HostEventDispatcher() override;
 
   // Set InputStub that will be called for each incoming input
   // message. Doesn't take ownership of |input_stub|. It must outlive
   // the dispatcher.
   void set_input_stub(InputStub* input_stub) { input_stub_ = input_stub; }
 
   // Set callback to notify of each message's sequence number. The
   // callback cannot tear down this object.
-  void set_event_timestamp_callback(const EventTimestampCallback& value) {
-    event_timestamp_callback_ = value;
+  void set_on_input_event_callback(const OnInputEventCallback& value) {
+    on_input_event_callback_ = value;
   }
 
  private:
   void OnMessageReceived(scoped_ptr<EventMessage> message,
                          const base::Closure& done_task);
 
   InputStub* input_stub_;
-  EventTimestampCallback event_timestamp_callback_;
+  OnInputEventCallback on_input_event_callback_;
 
   ProtobufMessageParser<EventMessage> parser_;
 
   DISALLOW_COPY_AND_ASSIGN(HostEventDispatcher);
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_HOST_EVENT_DISPATCHER_H_