Adding mojo MediaSessionClient to support media controls

third_party/WebKit/Source/modules/mediasession/MediaSession.cpp

Index: third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
diff --git a/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp b/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
index 0afbb0d8c1483b93121fc7f133fb10a5b3177c1b..af2ae8f94ff1df8ff4f934ebf11ab2582ddd4785 100644
--- a/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
+++ b/third_party/WebKit/Source/modules/mediasession/MediaSession.cpp
@@ -7,22 +7,77 @@
 #include "bindings/core/v8/ScriptState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
+#include "core/events/Event.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/EventTargetModules.h"
 #include "modules/mediasession/MediaMetadata.h"
 #include "modules/mediasession/MediaMetadataSanitizer.h"
 #include "public/platform/InterfaceProvider.h"
+#include "wtf/Optional.h"
 #include <memory>
 
 namespace blink {
 
+namespace {
+
+using ::blink::mojom::blink::MediaSessionAction;
+
+const AtomicString& mojomActionToEventName(MediaSessionAction action) {
+  switch (action) {
+    case MediaSessionAction::PLAY:
+      return EventTypeNames::play;
+    case MediaSessionAction::PAUSE:
+      return EventTypeNames::pause;
+    case MediaSessionAction::PLAY_PAUSE:
+      return EventTypeNames::playpause;
+    case MediaSessionAction::PREVIOUS_TRACK:
+      return EventTypeNames::previoustrack;
+    case MediaSessionAction::NEXT_TRACK:
+      return EventTypeNames::nexttrack;
+    case MediaSessionAction::SEEK_FORWARD:
+      return EventTypeNames::seekforward;
+    case MediaSessionAction::SEEK_BACKWARD:
+      return EventTypeNames::seekbackward;
+    default:
+      NOTREACHED();
+  }
+  return WTF::emptyAtom;
+}
+
+WTF::Optional<MediaSessionAction> eventNameToMojomAction(
+    const AtomicString& eventName) {
+  if (EventTypeNames::play == eventName)
+    return MediaSessionAction::PLAY;
+  if (EventTypeNames::pause == eventName)
+    return MediaSessionAction::PAUSE;
+  if (EventTypeNames::playpause == eventName)
+    return MediaSessionAction::PLAY_PAUSE;
+  if (EventTypeNames::previoustrack == eventName)
+    return MediaSessionAction::PREVIOUS_TRACK;
+  if (EventTypeNames::nexttrack == eventName)
+    return MediaSessionAction::NEXT_TRACK;
+  if (EventTypeNames::seekforward == eventName)
+    return MediaSessionAction::SEEK_FORWARD;
+  if (EventTypeNames::seekbackward == eventName)
+    return MediaSessionAction::SEEK_BACKWARD;
+
+  NOTREACHED();
+  return WTF::nullopt;
+}
+
+}  // anonymous namespace
+
 MediaSession::MediaSession(ScriptState* scriptState)
-    : m_scriptState(scriptState) {}
+    : m_scriptState(scriptState), m_clientBinding(this) {}
 
 MediaSession* MediaSession::create(ScriptState* scriptState) {
   return new MediaSession(scriptState);
 }
 
+void MediaSession::dispose() {
+  m_clientBinding.Close();
+}
+
 void MediaSession::setMetadata(MediaMetadata* metadata) {
   if (mojom::blink::MediaSessionService* service =
           getService(m_scriptState.get())) {
@@ -45,17 +100,23 @@ ExecutionContext* MediaSession::getExecutionContext() const {
 
 mojom::blink::MediaSessionService* MediaSession::getService(
     ScriptState* scriptState) {
-  if (!m_service) {
-    InterfaceProvider* interfaceProvider = nullptr;
-    DCHECK(scriptState->getExecutionContext()->isDocument())
-        << "MediaSession::getService() is only available from a frame";
-    Document* document = toDocument(scriptState->getExecutionContext());
-    if (document->frame())
-      interfaceProvider = document->frame()->interfaceProvider();
-
-    if (interfaceProvider)
-      interfaceProvider->getInterface(mojo::GetProxy(&m_service));
-  }
+  if (m_service)
+    return m_service.get();
+
+  DCHECK(scriptState->getExecutionContext()->isDocument())
+      << "MediaSession::getService() is only available from a frame";
+  Document* document = toDocument(scriptState->getExecutionContext());
+  if (!document->frame())
+    return nullptr;
+
+  InterfaceProvider* interfaceProvider = document->frame()->interfaceProvider();
+  if (!interfaceProvider)
+    return nullptr;
+
+  interfaceProvider->getInterface(mojo::GetProxy(&m_service));
+  if (m_service.get())
+    m_service->SetClient(m_clientBinding.CreateInterfacePtrAndBind());
+
   return m_service.get();
 }
 
@@ -63,8 +124,12 @@ bool MediaSession::addEventListenerInternal(
     const AtomicString& eventType,
     EventListener* listener,
     const AddEventListenerOptionsResolved& options) {
-  // TODO(zqzhang): Notify MediaSessionService the handler has been set. See
-  // https://crbug.com/656563
+  if (mojom::blink::MediaSessionService* service =
+          getService(m_scriptState.get())) {
+    auto mojomAction = eventNameToMojomAction(eventType);
+    DCHECK(mojomAction.has_value());
+    service->EnableAction(mojomAction.value());
+  }
   return EventTarget::addEventListenerInternal(eventType, listener, options);
 }
 
@@ -72,11 +137,20 @@ bool MediaSession::removeEventListenerInternal(
     const AtomicString& eventType,
     const EventListener* listener,
     const EventListenerOptions& options) {
-  // TODO(zqzhang): Notify MediaSessionService the handler has been unset. See
-  // https://crbug.com/656563
+  if (mojom::blink::MediaSessionService* service =
+          getService(m_scriptState.get())) {
+    auto mojomAction = eventNameToMojomAction(eventType);
+    DCHECK(mojomAction.has_value());
+    service->DisableAction(mojomAction.value());
+  }
   return EventTarget::removeEventListenerInternal(eventType, listener, options);
 }
 
+void MediaSession::DidReceiveAction(
+    blink::mojom::blink::MediaSessionAction action) {
+  dispatchEvent(Event::create(mojomActionToEventName(action)));
+}
+
 DEFINE_TRACE(MediaSession) {
   visitor->trace(m_metadata);
   EventTargetWithInlineData::trace(visitor);