Support unprefixed EME in HTMLViewer.

mojo/services/html_viewer/html_viewer.cc

Index: mojo/services/html_viewer/html_viewer.cc
diff --git a/mojo/services/html_viewer/html_viewer.cc b/mojo/services/html_viewer/html_viewer.cc
index fc69d33810ce241e1e3031db967b7ffbb00d3666..fae69bb9d8df4a9612ed31ce82d85f09eb9c53ec 100644
--- a/mojo/services/html_viewer/html_viewer.cc
+++ b/mojo/services/html_viewer/html_viewer.cc
@@ -22,6 +22,7 @@
 #include "mojo/services/html_viewer/webmediaplayer_factory.h"
 #include "mojo/services/network/public/interfaces/network_service.mojom.h"
 #include "third_party/WebKit/public/web/WebKit.h"
+#include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
 
 #if !defined(COMPONENT_BUILD)
 #include "base/i18n/icu_util.h"
@@ -48,6 +49,9 @@ namespace html_viewer {
 // media::Renderer implementation.
 const char kEnableMojoMediaRenderer[] = "enable-mojo-media-renderer";
 
+// Enables support for Encrypted Media Extensions (e.g. MediaKeys).
+const char kEnableEncryptedMedia[] = "enable-encrypted-media";
+
 class HTMLViewer;
 
 class HTMLViewerApplication : public mojo::Application {
@@ -174,6 +178,9 @@ class HTMLViewer : public mojo::ApplicationDelegate,
     bool enable_mojo_media_renderer =
         command_line->HasSwitch(kEnableMojoMediaRenderer);
 
+    if (command_line->HasSwitch(kEnableEncryptedMedia))
+      blink::WebRuntimeFeatures::enableEncryptedMedia(true);
+
     compositor_thread_.Start();
     web_media_player_factory_.reset(new WebMediaPlayerFactory(
         compositor_thread_.message_loop_proxy(), enable_mojo_media_renderer));