Plumb audio focus support for spitzer clients.

content/browser/media/media_web_contents_observer.cc

Index: content/browser/media/media_web_contents_observer.cc
diff --git a/content/browser/media/media_web_contents_observer.cc b/content/browser/media/media_web_contents_observer.cc
index 562836ebc33dc4146289b094915afe17c857084d..8cc985aa1d302c911bfdb53c85c175aedbfa1304 100644
--- a/content/browser/media/media_web_contents_observer.cc
+++ b/content/browser/media/media_web_contents_observer.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/media/media_web_contents_observer.h"
 
+#include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
 #include "content/browser/power_save_blocker_impl.h"
@@ -12,6 +13,7 @@
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "ipc/ipc_message_macros.h"
+#include "media/base/bind_to_current_loop.h"
 
 namespace content {
 
@@ -52,6 +54,49 @@ bool MediaWebContentsObserver::OnMessageReceived(
   return handled;
 }
 
+void MediaWebContentsObserver::WasShown() {
+  // Restore power save blocker if there are active video players running.
+  if (!active_video_players_.empty() && !video_power_save_blocker_)
+    CreateVideoPowerSaveBlocker();
+}
+
+void MediaWebContentsObserver::WasHidden() {
+  // If there are entities capturing screenshots or video (e.g., mirroring),
+  // don't release the power save blocker.
+  if (!web_contents()->GetCapturerCount())
+    video_power_save_blocker_.reset();
+}
+
+// static
+void MediaWebContentsObserver::HasAudioFocus(int render_process_id,
+                                             int render_frame_id,
+                                             const base::Closure& on_focus_cb) {
+  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&MediaWebContentsObserver::HasAudioFocus, render_process_id,
+                   render_frame_id, media::BindToCurrentLoop(on_focus_cb)));
+    return;
+  }
+
+  RenderFrameHost* rfh =
+      RenderFrameHost::FromID(render_process_id, render_frame_id);
+  if (rfh) {

[mlamouri (slow - plz ping), 2016/01/14 15:03:41]

nit:
```
if (!rfh)
  return;
```

Also, probably no need to null check `rfh`. `::FromRenderFrameHost()` will not
assume `rfh` is not null.

[DaleCurtis, 2016/01/14 23:16:10]

There was some reason I wrote it this way, but I don't see why now, so done.

+    WebContents* wc = WebContents::FromRenderFrameHost(rfh);

[mlamouri (slow - plz ping), 2016/01/14 15:03:41]

nit: we usually use `web_contents`, I can't remember seeing `wc` in the code
base.

[DaleCurtis, 2016/01/14 23:16:10]

Done.

+    if (wc) {

[mlamouri (slow - plz ping), 2016/01/14 15:03:41]

nit:
```
if (!wc)
  return;
```

[DaleCurtis, 2016/01/14 23:16:10]

Done.

+      MediaWebContentsObserver* p_this =
+          static_cast<WebContentsImpl*>(wc)->media_web_contents_observer();
+      p_this->CheckFocus(render_frame_id, on_focus_cb);
+      return;
+    }
+  }
+}
+
+void MediaWebContentsObserver::CheckFocus(int render_frame_id,
+                                          const base::Closure& on_focus_cb) {
+  NOTIMPLEMENTED();
+}
+
 void MediaWebContentsObserver::OnMediaDestroyedNotification(
     RenderFrameHost* render_frame_host,
     int64_t player_cookie) {
@@ -148,19 +193,6 @@ void MediaWebContentsObserver::CreateVideoPowerSaveBlocker() {
 #endif
 }
 
-void MediaWebContentsObserver::WasShown() {
-  // Restore power save blocker if there are active video players running.
-  if (!active_video_players_.empty() && !video_power_save_blocker_)
-    CreateVideoPowerSaveBlocker();
-}
-
-void MediaWebContentsObserver::WasHidden() {
-  // If there are entities capturing screenshots or video (e.g., mirroring),
-  // don't release the power save blocker.
-  if (!web_contents()->GetCapturerCount())
-    video_power_save_blocker_.reset();
-}
-
 void MediaWebContentsObserver::MaybeReleasePowerSaveBlockers() {
   // If there are no more audio players and we don't have audio stream
   // monitoring, release the audio power save blocker here instead of during