Record whether and why the media default controls are being shown.

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 0599ce2187e9d5ee7a4d68778485fd4a11fc5540..d93ac3aa197a78ed4255f2c6c97d2517fb3126b1 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -89,6 +89,18 @@
 
 namespace blink {
 
+namespace {
+
+enum DefaultControlsShow {

[philipj_slow, 2016/02/16 06:20:27]

I'd call it MediaControls, because these are the only controls that Blink knows
anything about. And enum class for less repetition?

[mlamouri (slow - plz ping), 2016/02/18 15:49:31]

Done.
enum class are not very friendly with macros so I would have to convert to int
when passing to the macro which would be... unfortunate :)

+    DefaultControlsShowAttribute = 0,
+    DefaultControlsShowFullscreen,
+    DefaultControlsShowNoScript,
+    DefaultControlsShowNone,
+    DefaultControlsShowMax
+};
+
+} // anonymous namespace

[philipj_slow, 2016/02/16 06:20:27]

Move the below static things into the anonymous namespace too? Nobody is ever
going to do it after this change. ("This looks strange, but there's probably a
good reason for it, never mind.")

[mlamouri (slow - plz ping), 2016/02/18 15:49:31]

I did that here: https://codereview.chromium.org/1710013002
This CL will be based on top of it.

+
 #if !LOG_DISABLED
 static String urlForLoggingMedia(const KURL& url)
 {
@@ -2091,6 +2103,30 @@ bool HTMLMediaElement::shouldShowControls() const
     return fastHasAttribute(controlsAttr);
 }
 
+void HTMLMediaElement::recordShowControls() const
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, showControlsHistogram, ("Media.Controls.Show", DefaultControlsShowMax));
+
+    if (fastHasAttribute(controlsAttr)) {

[philipj_slow, 2016/02/16 06:20:27]

Duplicating the conditions of shouldShowControls() but in a different order
makes it non-obvious that it's precisely correct, and that should be trivial. Is
it separate for performance concerns? If so, make shouldShowControls() return an
enum value which is just treated as bool everywhere except before
mediaControls()->show(), where it's used to count?

[mlamouri (slow - plz ping), 2016/02/18 15:49:31]

Fixed. I know have an internal show controls that record the result.

+        showControlsHistogram.count(DefaultControlsShowAttribute);
+        return;
+    }
+
+    if (isFullscreen()) {
+        showControlsHistogram.count(DefaultControlsShowFullscreen);
+        return;
+    }
+
+    LocalFrame* frame = document().frame();
+    if (frame && !frame->script().canExecuteScripts(NotAboutToExecuteScript)) {
+        showControlsHistogram.count(DefaultControlsShowNoScript);
+        return;
+    }
+
+    ASSERT(!shouldShowControls());
+    showControlsHistogram.count(DefaultControlsShowNone);
+}
+
 double HTMLMediaElement::volume() const
 {
     return m_volume;
@@ -3343,6 +3379,8 @@ void HTMLMediaElement::configureMediaControls()
 
     ensureMediaControls();
     mediaControls()->reset();
+
+    recordShowControls();
     if (shouldShowControls())
         mediaControls()->show();
     else