[Media Controls] Add UMA for timeline scrubber

third_party/WebKit/Source/core/html/shadow/MediaControlElements.h

Index: third_party/WebKit/Source/core/html/shadow/MediaControlElements.h
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.h b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.h
index df272a9493bee9dd77330ad7c5154beb82b50715..fe766e76dc08a02511caedf8a05affe6baecfa68 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.h
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.h
@@ -31,6 +31,7 @@
 #define MediaControlElements_h
 
 #include "core/html/shadow/MediaControlElementTypes.h"
+#include "core/html/shadow/MediaControlTimelineMetrics.h"
 #include "public/platform/WebLocalizedString.h"
 
 namespace blink {
@@ -273,11 +274,20 @@ class MediaControlTimelineElement final : public MediaControlInputElement {
   void setPosition(double);
   void setDuration(double);
 
+  // Logs width to UMA. Should be called the first time the media is played.
+  void recordWidthOnFirstPlay();
+
  private:
   explicit MediaControlTimelineElement(MediaControls&);
 
   void defaultEventHandler(Event*) override;
   bool keepEventInNode(Event*) override;
+
+  // Width in CSS pixels * pageZoomFactor (ignores CSS transforms for
+  // simplicity; deliberately ignores pinch zoom's pageScaleFactor).
+  int timelineWidth();

[mlamouri (slow - plz ping), 2017/03/30 21:43:00]

getTimelineWidth() to be more Chromium friendly? :)

[johnme, 2017/03/31 13:47:23]

Blink style guide says not to:
https://sites.google.com/a/chromium.org/dev/blink/coding-style
[names-setter-getter]

+
+  MediaControlTimelineMetrics m_metrics;
 };
 
 // ----------------------------