[Media Controls] Add UMA for rotate-to-fullscreen feature

third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp

Index: third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp
diff --git a/third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp b/third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp
index bc5ab11aac7fbfd432ed0b52a8d9039772c4e4b3..e15b5d0677a0c694813d99fede1f608a9e9983a1 100644
--- a/third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp
+++ b/third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp
@@ -72,6 +72,13 @@ void RecordLockResult(LockResultMetrics metrics) {
   lock_result_histogram.Count(static_cast<int>(metrics));
 }
 
+void RecordAutoRotateEnabled(bool enabled) {
+  DEFINE_STATIC_LOCAL(
+      BooleanHistogram, auto_rotate_histogram,
+      ("Media.Video.FullscreenOrientationLock.AutoRotateEnabled"));
+  auto_rotate_histogram.Count(enabled);
+}
+
 // WebLockOrientationCallback implementation that will not react to a success
 // nor a failure.
 class DummyScreenOrientationCallback : public WebLockOrientationCallback {
@@ -210,6 +217,8 @@ void MediaControlsOrientationLockDelegate::GotIsAutoRotateEnabledByUser(
     bool enabled) {
   monitor_.reset();
 
+  RecordAutoRotateEnabled(enabled);
+
   if (!enabled) {
     // Since the user has locked their screen orientation, prevent
     // MediaControlsRotateToFullscreenDelegate from exiting fullscreen by not