Plumb audio focus support for spitzer clients.

content/browser/media/android/media_web_contents_observer_android.cc

Index: content/browser/media/android/media_web_contents_observer_android.cc
diff --git a/content/browser/media/android/media_web_contents_observer_android.cc b/content/browser/media/android/media_web_contents_observer_android.cc
index aa66741fd92fe0de407e3498f4281d59a11fecfc..b14945bba7f18a6fefe5b94a41cad8250f6b34ef 100644
--- a/content/browser/media/android/media_web_contents_observer_android.cc
+++ b/content/browser/media/android/media_web_contents_observer_android.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/media/android/media_web_contents_observer_android.h"
 
+#include "base/callback.h"
 #include "content/browser/media/android/browser_media_player_manager.h"
 #include "content/browser/media/android/browser_media_session_manager.h"
 #include "content/browser/media/android/media_session.h"
@@ -199,6 +200,19 @@ bool MediaWebContentsObserverAndroid::OnMessageReceived(
   return OnMediaPlayerSetCdmMessageReceived(msg, render_frame_host);
 }
 
+void MediaWebContentsObserverAndroid::CheckFocus(
+    int render_frame_id,
+    const base::Closure& on_focus_cb) {
+  for (const auto& kv : media_session_map_) {
+    if (kv.first.first->GetRoutingID() == render_frame_id) {
+      on_focus_cb.Run();
+      return;
+    }
+  }
+
+  deferred_focus_cbs_[render_frame_id].push_back(on_focus_cb);
+}
+
 void MediaWebContentsObserverAndroid::OnMediaPlayerDelegateMessageReceived(
     const IPC::Message& msg,
     RenderFrameHost* render_frame_host) {
@@ -316,6 +330,7 @@ void MediaWebContentsObserverAndroid::OnMediaDestroyedNotification(
     RenderFrameHost* render_frame_host,
     int64_t player_cookie) {
   media_session_map_.erase(MediaPlayerId(render_frame_host, player_cookie));
+  deferred_focus_cbs_.erase(render_frame_host->GetRoutingID());
 }
 
 void MediaWebContentsObserverAndroid::OnMediaPlayingNotification(
@@ -339,6 +354,14 @@ void MediaWebContentsObserverAndroid::OnMediaPlayingNotification(
     return;
 
   media_session_map_[id] = std::move(controller);
+
+  // Notify any deferred focus callbacks.
+  auto it = deferred_focus_cbs_.find(render_frame_host->GetRoutingID());
+  if (it != deferred_focus_cbs_.end()) {
+    for (const auto& cb : it->second)
+      cb.Run();
+    deferred_focus_cbs_.erase(it);
+  }
 }
 
 void MediaWebContentsObserverAndroid::OnMediaPausedNotification(