Create an interface for KeySystems, migrate WebEncryptedMediaClientImpl.

mojo/services/html_viewer/html_document.cc

Index: mojo/services/html_viewer/html_document.cc
diff --git a/mojo/services/html_viewer/html_document.cc b/mojo/services/html_viewer/html_document.cc
index 150a8e1010bef29e97cdceb934181fbcc4e07307..daade4ea0b43c1fdd10e55a6e2fb1fd73ed209d7 100644
--- a/mojo/services/html_viewer/html_document.cc
+++ b/mojo/services/html_viewer/html_document.cc
@@ -12,6 +12,7 @@
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/thread_task_runner_handle.h"
+#include "media/base/key_systems.h"
 #include "media/blink/webencryptedmediaclient_impl.h"
 #include "media/cdm/default_cdm_factory.h"
 #include "media/filters/default_media_permission.h"
@@ -286,6 +287,7 @@ blink::WebEncryptedMediaClient* HTMLDocument::encryptedMediaClient() {
     if (!media_permission_)
       media_permission_.reset(new media::DefaultMediaPermission(true));
     web_encrypted_media_client_.reset(new media::WebEncryptedMediaClientImpl(
+        media::KeySystems::GetInstance(),
         make_scoped_ptr(new media::DefaultCdmFactory()),
         media_permission_.get()));
   }