Add Keyboard Latency UMA Metrics.

ui/events/event.cc

 // 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.
 
 #include "ui/events/event.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 
@@ skipping 131 matching lines @@
     case ET_GESTURE_PINCH_UPDATE:
     case ET_GESTURE_LONG_PRESS:
     case ET_GESTURE_LONG_TAP:
     case ET_GESTURE_SWIPE:
     case ET_GESTURE_SHOW_PRESS:
     // Flings can be GestureEvents too.
     case ET_SCROLL_FLING_START:
     case ET_SCROLL_FLING_CANCEL:
       return SourceEventType::UNKNOWN;
 
+    case ui::ET_KEY_PRESSED:
+      return ui::SourceEventType::KEY;
+
     case ET_MOUSE_PRESSED:
     case ET_MOUSE_DRAGGED:
     case ET_MOUSE_RELEASED:
     case ET_MOUSE_MOVED:
     case ET_MOUSE_ENTERED:
     case ET_MOUSE_EXITED:
-    case ET_KEY_PRESSED:
+    // We measure latency for key presses, not key releases. Most behavior is

[mfomitchev, 2017/04/04 14:59:06]

Nit: Perhaps this comment should be in the SourceEventType enum? We can leave
something here as well.

[tdresser, 2017/05/01 15:49:21]

Added a comment in SourceEventType enum.

+    // keyed off of presses, and release latency is higher than press latency as
+    // it's impacted by event handling of the press event.
     case ET_KEY_RELEASED:
     case ET_MOUSE_CAPTURE_CHANGED:
     case ET_DROP_TARGET_EVENT:
     case ET_CANCEL_MODE:
     case ET_UMA_DATA:
       return SourceEventType::OTHER;
 
     case ET_TOUCH_RELEASED:
     case ET_TOUCH_PRESSED:
     case ET_TOUCH_MOVED:
@@ skipping 964 matching lines @@
 }
 
 KeyEvent::KeyEvent(const base::NativeEvent& native_event)
     : KeyEvent(native_event, EventFlagsFromNative(native_event)) {}
 
 KeyEvent::KeyEvent(const base::NativeEvent& native_event, int event_flags)
     : Event(native_event, EventTypeFromNative(native_event), event_flags),
       key_code_(KeyboardCodeFromNative(native_event)),
       code_(CodeFromNative(native_event)),
       is_char_(IsCharFromNative(native_event)) {
+  latency()->AddLatencyNumberWithTimestamp(
+      INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT, 0, 0,
+      base::TimeTicks::FromInternalValue(time_stamp().ToInternalValue()), 1);
+  latency()->AddLatencyNumber(INPUT_EVENT_LATENCY_UI_COMPONENT, 0, 0);
+
   if (IsRepeated(*this))
     set_flags(flags() | ui::EF_IS_REPEAT);
 
 #if defined(USE_X11)
   NormalizeFlags();
 #endif
 #if defined(OS_WIN)
   // Only Windows has native character events.
   if (is_char_)
     key_ = DomKey::FromCharacter(native_event.wParam);
@@ skipping 292 matching lines @@
                    flags | EF_FROM_TOUCH),
       details_(details),
       unique_touch_event_id_(unique_touch_event_id) {
   latency()->set_source_event_type(ui::SourceEventType::TOUCH);
 }
 
 GestureEvent::~GestureEvent() {
 }
 
 }  // namespace ui