[Media Controls] Add UMA for timeline scrubber

third_party/WebKit/Source/core/html/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/split_static_library.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("html") {
   split_count = 5
 
@@ skipping 457 matching lines @@
     "shadow/DateTimeNumericFieldElement.cpp",
     "shadow/DateTimeNumericFieldElement.h",
     "shadow/DateTimeSymbolicFieldElement.cpp",
     "shadow/DateTimeSymbolicFieldElement.h",
     "shadow/DetailsMarkerControl.cpp",
     "shadow/DetailsMarkerControl.h",
     "shadow/MediaControlElementTypes.cpp",
     "shadow/MediaControlElementTypes.h",
     "shadow/MediaControlElements.cpp",
     "shadow/MediaControlElements.h",
+    "shadow/MediaControlTimelineMetrics.cpp",
+    "shadow/MediaControlTimelineMetrics.h",
     "shadow/MediaControlsMediaEventListener.cpp",
     "shadow/MediaControlsMediaEventListener.h",
     "shadow/MediaControlsWindowEventListener.cpp",
     "shadow/MediaControlsWindowEventListener.h",
     "shadow/PickerIndicatorElement.cpp",
     "shadow/PickerIndicatorElement.h",
     "shadow/ProgressShadowElement.cpp",
     "shadow/ProgressShadowElement.h",
     "shadow/ShadowElementNames.cpp",
     "shadow/ShadowElementNames.h",
@@ skipping 50 matching lines @@
     "track/vtt/VTTToken.h",
     "track/vtt/VTTTokenizer.cpp",
     "track/vtt/VTTTokenizer.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }