media: Add UMA to record whether encrypted media is enabled

third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp

 // Copyright 2014 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.
 
 #include "modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.h"
 
 #include <algorithm>
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
@@ skipping 260 matching lines @@
   Document* document = ToDocument(execution_context);
 
   // From https://w3c.github.io/encrypted-media/#common-key-systems
   // All user agents MUST support the common key systems described in this
   // section.
   // 9.1 Clear Key: The "org.w3.clearkey" Key System uses plain-text clear
   //                (unencrypted) key(s) to decrypt the source.
   //
   // Do not check settings for Clear Key.
   if (key_system != "org.w3.clearkey") {
-    // For other key systems, check settings.
-    if (!document->GetSettings() ||
-        !document->GetSettings()->GetEncryptedMediaEnabled()) {
+    // For other key systems, check settings and report UMA.
+    bool encypted_media_enabled =
+        document->GetSettings() &&
+        document->GetSettings()->GetEncryptedMediaEnabled();
+
+    static bool has_reported_uma = false;
+    if (!has_reported_uma) {
+      has_reported_uma = true;
+      DEFINE_STATIC_LOCAL(BooleanHistogram, histogram,
+                          ("Media.EME.EncryptedMediaEnabled"));
+      histogram.Count(encypted_media_enabled);
+    }
+
+    if (!encypted_media_enabled) {
       return ScriptPromise::RejectWithDOMException(
           script_state,
           DOMException::Create(kNotSupportedError, "Unsupported keySystem"));
     }
   }
 
   // From https://w3c.github.io/encrypted-media/#requestMediaKeySystemAccess
   // When this method is invoked, the user agent must run the following steps:
   // 1. If keySystem is the empty string, return a promise rejected with a
   //    newly created TypeError.
@@ skipping 39 matching lines @@
   WebEncryptedMediaClient* media_client =
       controller->EncryptedMediaClient(execution_context);
   media_client->RequestMediaKeySystemAccess(
       WebEncryptedMediaRequest(initializer));
 
   // 7. Return promise.
   return promise;
 }
 
 }  // namespace blink