[Media Session] Fix Android Jumbo build

Fix Android jumbo build.

BUG=876227

Change-Id: Iabe7d634e2019ac15993ac53570b7c20e581549f
Reviewed-on: https://chromium-review.googlesource.com/1192118Reviewed-by: John Rummell <jrummell@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586765}

content/browser/media/session/audio_focus_delegate_android.h

@@ -18,8 +18,6 @@ enum class AudioFocusType;
 
 namespace content {
 
-enum class AudioFocusType;
-
 // AudioFocusDelegateAndroid handles the audio focus at a system level on
 // Android. It is also proxying the JNI calls.
 class AudioFocusDelegateAndroid : public AudioFocusDelegate {