Presentation API: reject screen availability observing on Android low ram devices.

chrome/browser/media/router/presentation_service_delegate_impl.cc

Index: chrome/browser/media/router/presentation_service_delegate_impl.cc
diff --git a/chrome/browser/media/router/presentation_service_delegate_impl.cc b/chrome/browser/media/router/presentation_service_delegate_impl.cc
index e03063d83228cd22368d63c42e78bebb6675992a..e2010440ff76b1e2ebe1828dd2dd756b2e24daf4 100644
--- a/chrome/browser/media/router/presentation_service_delegate_impl.cc
+++ b/chrome/browser/media/router/presentation_service_delegate_impl.cc
@@ -178,12 +178,19 @@ const std::vector<MediaRoute::Id> PresentationFrame::GetRouteIds() const {
 
 bool PresentationFrame::SetScreenAvailabilityListener(
     content::PresentationScreenAvailabilityListener* listener) {
-  if (sinks_observer_ && sinks_observer_->listener() == listener) {
+  if (sinks_observer_ && sinks_observer_->listener() == listener)
     return false;
-  }
+
   MediaSource source(GetMediaSourceFromListener(listener));
   sinks_observer_.reset(
       new PresentationMediaSinksObserver(router_, listener, source));
+
+  if (!sinks_observer_->is_active()) {

[mark a. foltz, 2015/10/01 18:33:28]

It's slightly weird that you are creating a sinks observer, only to immediately
destroy it because the router created it as inactive.

I believe this is because we do the registration/unregistration in the
MediaSinksObserver ctor/dtor.  Some refactoring to allow the router to create
one (or refuse to) instead would probably make this clearer.

However, not necessary to land this - out of scope for this fix anyway.

[mlamouri (slow - plz ping), 2015/10/01 21:40:45]

Anton made the same comment and we considered using a ::Create() static method
but that is a bit complex given that there are MediaSinksObserver and
PresentationMediaSinksObserver. This is something we might look into later.

+    sinks_observer_.reset();
+    listener->OnScreenAvailabilityNotSupported();
+    return false;
+  }
+
   return true;
 }