Add Stubbed implementation of WebCDM* interfaces for unprefixed EME APIs.

content/renderer/renderer_webkitplatformsupport_impl.cc

Index: content/renderer/renderer_webkitplatformsupport_impl.cc
diff --git a/content/renderer/renderer_webkitplatformsupport_impl.cc b/content/renderer/renderer_webkitplatformsupport_impl.cc
index 3460004c63dd0797edb14b15ca396278b4dafb2a..9340b4680560cf8364ee88a7c50eebe8595c5d48 100644
--- a/content/renderer/renderer_webkitplatformsupport_impl.cc
+++ b/content/renderer/renderer_webkitplatformsupport_impl.cc
@@ -31,6 +31,7 @@
 #include "content/renderer/hyphenator/hyphenator.h"
 #include "content/renderer/media/media_stream_dependency_factory.h"
 #include "content/renderer/media/renderer_webaudiodevice_impl.h"
+#include "content/renderer/media/webcontentdecryptionmodule_impl.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/renderer_clipboard_client.h"
 #include "content/renderer/websharedworkerrepository_impl.h"
@@ -732,6 +733,14 @@ RendererWebKitPlatformSupportImpl::createAudioDevice(
 
 //------------------------------------------------------------------------------
 
+WebKit::WebContentDecryptionModule*
+RendererWebKitPlatformSupportImpl::createContentDecryptionModule(
+    const WebKit::WebString& key_system) {
+  return WebContentDecryptionModuleImpl::Create(key_system);
+}
+
+//------------------------------------------------------------------------------
+
 WebKit::WebString
 RendererWebKitPlatformSupportImpl::signedPublicKeyAndChallengeString(
     unsigned key_size_index,