Detect change on video/viewport intersection when rendered remotely

media/remoting/remoting_renderer_controller.cc

Index: media/remoting/remoting_renderer_controller.cc
diff --git a/media/remoting/remoting_renderer_controller.cc b/media/remoting/remoting_renderer_controller.cc
index f1abc93d3a6b4531a8c22f7fdf8fae7f46e0fd76..7b542946f58c4bcd05e4dce7b3e4d7fc706adce6 100644
--- a/media/remoting/remoting_renderer_controller.cc
+++ b/media/remoting/remoting_renderer_controller.cc
@@ -43,9 +43,27 @@ void RemotingRendererController::OnSessionStateChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   VLOG(1) << "OnSessionStateChanged: " << remoting_source_->state();
+  if (!sink_available_changed_cb_.is_null())
+    sink_available_changed_cb_.Run(IsRemoteSinkAvailable());
+
   UpdateAndMaybeSwitch();
 }
 
+bool RemotingRendererController::IsRemoteSinkAvailable() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  switch (remoting_source_->state()) {
+    case SESSION_CAN_START:
+    case SESSION_STARTING:
+    case SESSION_STARTED:
+      return true;
+    case SESSION_UNAVAILABLE:
+    case SESSION_STOPPING:
+    case SESSION_PERMANENTLY_STOPPED:
+      return false;
+  }
+}
+
 void RemotingRendererController::OnEnteredFullscreen() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
@@ -96,6 +114,15 @@ void RemotingRendererController::SetSwitchRendererCallback(
   UpdateAndMaybeSwitch();
 }
 
+void RemotingRendererController::SetRemoteSinkAvailableChangedCallback(
+    const base::Callback<void(bool)>& cb) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!cb.is_null());

[miu, 2016/12/10 02:18:37]

nit: It's probably okay for this to be a null callback, if client code ever
wants to "unset" the callback.

[xjz, 2016/12/12 18:58:45]

Done.

+
+  sink_available_changed_cb_ = cb;
+  sink_available_changed_cb_.Run(IsRemoteSinkAvailable());
+}
+
 base::WeakPtr<remoting::RpcBroker> RemotingRendererController::GetRpcBroker()
     const {
   DCHECK(thread_checker_.CalledOnValidThread());