Add Keyboard Latency UMA Metrics.

ui/events/latency_info.h

 // Copyright 2013 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 UI_EVENTS_LATENCY_INFO_H_
 #define UI_EVENTS_LATENCY_INFO_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 91 matching lines @@
   // but the swap failed.
   INPUT_EVENT_LATENCY_TERMINATED_SWAP_FAILED_COMPONENT,
   LATENCY_COMPONENT_TYPE_LAST =
       INPUT_EVENT_LATENCY_TERMINATED_SWAP_FAILED_COMPONENT,
 };
 
 enum SourceEventType {
   UNKNOWN,
   WHEEL,
   TOUCH,
+  KEY,
   OTHER,
   SOURCE_EVENT_TYPE_LAST = OTHER,
 };
 
 class EVENTS_BASE_EXPORT LatencyInfo {
  public:
   struct LatencyComponent {
     // Nondecreasing number that can be used to determine what events happened
     // in the component at the time this struct was sent on to the next
     // component.
@@ skipping 131 matching lines @@
 #if !defined(OS_IOS)
   friend struct IPC::ParamTraits<ui::LatencyInfo>;
   friend struct mojo::StructTraits<ui::mojom::LatencyInfoDataView,
                                    ui::LatencyInfo>;
 #endif
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_LATENCY_INFO_H_