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

chrome/browser/media/router/media_router_mojo_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/media/router/media_router_mojo_impl.h"
 
 #include "base/bind.h"
 #include "base/guid.h"
 #include "base/logging.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 257 matching lines @@
   issue_manager_.ClearIssue(issue_id);
 }
 
 void MediaRouterMojoImpl::OnPresentationSessionDetached(
     const MediaRoute::Id& route_id) {
   DCHECK(thread_checker_.CalledOnValidThread());
   RunOrDefer(base::Bind(&MediaRouterMojoImpl::DoOnPresentationSessionDetached,
                         base::Unretained(this), route_id));
 }
 
-void MediaRouterMojoImpl::RegisterMediaSinksObserver(
+bool MediaRouterMojoImpl::RegisterMediaSinksObserver(
     MediaSinksObserver* observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // Create an observer list for the media source and add |observer|
   // to it. Fail if |observer| is already registered.
   const std::string& source_id = observer->source().id();
   base::ObserverList<MediaSinksObserver>* observer_list =
       sinks_observers_.get(source_id);
   if (!observer_list) {
     observer_list = new base::ObserverList<MediaSinksObserver>;
     sinks_observers_.add(source_id, make_scoped_ptr(observer_list));
   } else {
     DCHECK(!observer_list->HasObserver(observer));
   }
 
   // We need to call DoStartObservingMediaSinks every time an observer is
   // added to ensure the observer will be notified with a fresh set of results.
   // TODO(imcheng): Implement caching. (crbug.com/492451)
   observer_list->AddObserver(observer);
   RunOrDefer(base::Bind(&MediaRouterMojoImpl::DoStartObservingMediaSinks,
                         base::Unretained(this), source_id));
+  return true;
 }
 
 void MediaRouterMojoImpl::UnregisterMediaSinksObserver(
     MediaSinksObserver* observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const MediaSource::Id& source_id = observer->source().id();
   auto* observer_list = sinks_observers_.get(source_id);
   if (!observer_list || !observer_list->HasObserver(observer)) {
     return;
@@ skipping 273 matching lines @@
     return;
   }
 
   for (const auto& next_request : pending_requests_)
     next_request.Run();
 
   pending_requests_.clear();
 }
 
 }  // namespace media_router