Media Capabilities: add plumbing between Blink and media/blink/.

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 0eaf473389ffc81eef95798c673dd42ae1b9ee11..75990c6453bb6d733ab278b4024ff787c494ae8f 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -739,6 +739,11 @@ blink::WebPushProvider* BlinkPlatformImpl::pushProvider() {
   return PushProvider::ThreadSpecificInstance(main_thread_task_runner_);
 }
 
+blink::WebMediaCapabilitiesClient*
+BlinkPlatformImpl::mediaCapabilitiesClient() {
+  return &media_capabilities_client_;
+}
+
 WebThemeEngine* BlinkPlatformImpl::themeEngine() {
   return &native_theme_engine_;
 }