Record the type of controls used for video persistence.

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index 7fa17e2b42c67ae4901a253a4c08bc9aabcc3cd6..ca4f359316b3defde3417bdb248efa20574b8c30 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -130,6 +130,7 @@ constexpr float kMostlyFillViewportThreshold = 0.85f;
 constexpr double kMostlyFillViewportBecomeStableSeconds = 5;
 constexpr double kCheckViewportIntersectionIntervalSeconds = 1;
 
+// This enum is used to record histograms. Do not reorder.
 enum MediaControlsShow {
   MediaControlsShowAttribute = 0,
   MediaControlsShowFullscreen,
@@ -139,6 +140,13 @@ enum MediaControlsShow {
   MediaControlsShowMax
 };
 
+// This enum is used to record histograms. Do not reorder.
+enum VideoPersistenceControlsType {
+  VideoPersistenceControlsTypeNative = 0,
+  VideoPersistenceControlsTypeCustom,
+  VideoPersistenceControlsTypeMax

[Ilya Sherman, 2017/03/20 19:08:39]

Optional nit: Typically, this would be named "Count" rather than "Max" -- "max"
is usually equal to the last actual item of the enum, whereas this is
max-plus-one (which is what histograms need).

[Zhiqiang Zhang (Slow), 2017/03/20 21:29:15]

Or name it "NumberOfTypes"?
Also, use "enum class" maybe?

[mlamouri (slow - plz ping), 2017/03/21 12:01:21]

Named it Count as per isherman@ request. I would like to use an enum class but
the histogram code doesn't like enum class and it would forces us to do static
cast int which, given what we are doing with the enum, sounds like mostly
useless.

+};
+
 String urlForLoggingMedia(const KURL& url) {
   static const unsigned maximumURLLengthForLogging = 128;
 
@@ -3242,6 +3250,17 @@ void HTMLMediaElement::onBecamePersistentVideo(bool value) {
     return;
 
   if (value) {
+    // Record the type of video. If it is already fullscreen, it is a video with
+    // native controls, otherwise it is assumed to be with custom controls.
+    // This is only recorded when entering this mode.
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram,
+                        ("Media.VideoPersistence.ControlsType",
+                         VideoPersistenceControlsTypeMax));
+    if (isFullscreen())
+      histogram.count(VideoPersistenceControlsTypeNative);
+    else
+      histogram.count(VideoPersistenceControlsTypeCustom);
+
     if (isFullscreen())
       return;