media: Add a web preference to enable encrypted media

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"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/V8ThrowException.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/Deprecation.h"
+#include "core/frame/Settings.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "modules/encryptedmedia/EncryptedMediaUtils.h"
 #include "modules/encryptedmedia/MediaKeySession.h"
 #include "modules/encryptedmedia/MediaKeySystemAccess.h"
 #include "modules/encryptedmedia/MediaKeysController.h"
 #include "platform/EncryptedMediaRequest.h"
 #include "platform/Histogram.h"
 #include "platform/network/ParsedContentType.h"
 #include "public/platform/WebEncryptedMediaClient.h"
 #include "public/platform/WebEncryptedMediaRequest.h"
 #include "public/platform/WebMediaKeySystemConfiguration.h"
 #include "public/platform/WebMediaKeySystemMediaCapability.h"
 #include "public/platform/WebVector.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
-#include <algorithm>
 
 namespace blink {
 
 namespace {
 
 static WebVector<WebEncryptedMediaInitDataType> convertInitDataTypes(
     const Vector<String>& initDataTypes) {
   WebVector<WebEncryptedMediaInitDataType> result(initDataTypes.size());
   for (size_t i = 0; i < initDataTypes.size(); ++i)
     result[i] = EncryptedMediaUtils::convertToInitDataType(initDataTypes[i]);
@@ skipping 255 matching lines @@
 
 }  // namespace
 
 ScriptPromise NavigatorRequestMediaKeySystemAccess::requestMediaKeySystemAccess(
     ScriptState* scriptState,
     Navigator& navigator,
     const String& keySystem,
     const HeapVector<MediaKeySystemConfiguration>& supportedConfigurations) {
   DVLOG(3) << __func__;
 
+  ExecutionContext* executionContext = scriptState->getExecutionContext();
+  Document* document = toDocument(executionContext);
+
+  // If encrypted media is disabled, return a rejected promise.
+  if (!document->settings() ||
+      !document->settings()->getEncryptedMediaEnabled()) {
+    return ScriptPromise::rejectWithDOMException(
+        scriptState, DOMException::create(NotSupportedError,
+                                          "Encrypted media is disabled."));
+  }
+
   // 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.
   if (keySystem.isEmpty()) {
     return ScriptPromise::reject(
         scriptState,
         V8ThrowException::createTypeError(scriptState->isolate(),
                                           "The keySystem parameter is empty."));
   }
 
   // 2. If supportedConfigurations is empty, return a promise rejected with
   //    a newly created TypeError.
   if (!supportedConfigurations.size()) {
     return ScriptPromise::reject(
         scriptState, V8ThrowException::createTypeError(
                          scriptState->isolate(),
                          "The supportedConfigurations parameter is empty."));
   }
 
   // Note: This method should only be exposed to secure contexts as indicated
   // by the [SecureContext] IDL attribute. Since that will break some existing
   // sites, we simply keep track of sites that aren't secure and output a
   // deprecation message.
-  ExecutionContext* executionContext = scriptState->getExecutionContext();
   if (executionContext->isSecureContext()) {
     UseCounter::count(executionContext, UseCounter::EncryptedMediaSecureOrigin);
   } else {
     Deprecation::countDeprecation(executionContext,
                                   UseCounter::EncryptedMediaInsecureOrigin);
     // TODO(ddorwin): Implement the following:
     // Reject promise with a new DOMException whose name is NotSupportedError.
   }
 
   // 3. Let document be the calling context's Document.
-  Document* document = toDocument(executionContext);
+  //    (Done at the begining of this function.)
   if (!document->page()) {
     return ScriptPromise::rejectWithDOMException(
         scriptState,
         DOMException::create(
             InvalidStateError,
             "The context provided is not associated with a page."));
   }
 
   // 4. Let origin be the origin of document.
   //    (Passed with the execution context.)
@@ skipping 10 matching lines @@
   WebEncryptedMediaClient* mediaClient =
       controller->encryptedMediaClient(executionContext);
   mediaClient->requestMediaKeySystemAccess(
       WebEncryptedMediaRequest(initializer));
 
   // 7. Return promise.
   return promise;
 }
 
 }  // namespace blink