Fixes unused variable in MediaWebContentsObserver.

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 7f9e2b65564847fda42fe3694d5664ccca364292..3036676ffceb4639162778fc6e15ef83837d48c0 100644
--- a/content/browser/media/media_web_contents_observer.cc
+++ b/content/browser/media/media_web_contents_observer.cc
@@ -30,10 +30,10 @@ MediaWebContentsObserver::~MediaWebContentsObserver() {
 
 void MediaWebContentsObserver::RenderFrameDeleted(
     RenderFrameHost* render_frame_host) {
+#if defined(OS_ANDROID)
   uintptr_t key = reinterpret_cast<uintptr_t>(render_frame_host);
   // Always destroy the media players before CDMs because we do not support
   // detaching CDMs from media players yet. See http://crbug.com/330324
-#if defined(OS_ANDROID)
   media_player_managers_.erase(key);
 #endif
   // TODO(xhwang): Currently MediaWebContentsObserver, BrowserMediaPlayerManager