Cleanup: IWYU for base/gtest_prod_util.h.

media/audio/android/audio_manager_android.h

Index: media/audio/android/audio_manager_android.h
diff --git a/media/audio/android/audio_manager_android.h b/media/audio/android/audio_manager_android.h
index c64e6ee267de608aea7c3a0da25bd77c43acd980..87745b2a06bd59759e724ba9f2204fad253b7fa2 100644
--- a/media/audio/android/audio_manager_android.h
+++ b/media/audio/android/audio_manager_android.h
@@ -8,7 +8,6 @@
 #include <set>
 
 #include "base/android/jni_android.h"
-#include "base/gtest_prod_util.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "media/audio/audio_manager_base.h"
@@ -20,7 +19,7 @@ class OpenSLESOutputStream;
 // Android implemention of AudioManager.
 class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
  public:
-  AudioManagerAndroid(AudioLogFactory* audio_log_factory);
+  explicit AudioManagerAndroid(AudioLogFactory* audio_log_factory);
 
   // Implementation of AudioManager.
   bool HasAudioOutputDevices() override;