Intiialize AudioManager and related class lazily

media/audio/android/audio_manager_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/android/audio_manager_android.h"
 
 #include "base/android/build_info.h"
 #include "base/android/context_utils.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
@@ skipping 45 matching lines @@
 
 AudioManagerAndroid::AudioManagerAndroid(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
     AudioLogFactory* audio_log_factory)
     : AudioManagerBase(std::move(task_runner),
                        std::move(worker_task_runner),
                        audio_log_factory),
       communication_mode_is_on_(false),
       output_volume_override_set_(false),
-      output_volume_override_(0) {
+      output_volume_override_(0),
+      initialized_(false) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
+}
+
+AudioManagerAndroid::~AudioManagerAndroid() {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  Shutdown();
+
+  if (j_audio_manager_.is_null())
+    return;
+  DVLOG(2) << "Destroying Java part of the audio manager";
+  Java_AudioManagerAndroid_close(base::android::AttachCurrentThread(),
+                                 j_audio_manager_.obj());
+  j_audio_manager_.Reset();
+}
+
+void AudioManagerAndroid::InitializeIfNeeded() {
+  if (initialized_)
+    return;
 
   // WARNING: This is executed on the UI loop, do not add any code here which
-  // loads libraries or attempts to call out into the OS.  Instead add such code
+  // loads libraries or attempts to call out into the OS. Instead add such code
   // to the InitializeOnAudioThread() method below.
 
   // Task must be posted last to avoid races from handing out "this" to the
   // audio thread.
   GetTaskRunner()->PostTask(FROM_HERE, base::Bind(
       &AudioManagerAndroid::InitializeOnAudioThread,
       base::Unretained(this)));
-}
-
-AudioManagerAndroid::~AudioManagerAndroid() {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  Shutdown();
-
-  DVLOG(2) << "Destroying Java part of the audio manager";
-  Java_AudioManagerAndroid_close(base::android::AttachCurrentThread(),
-                                 j_audio_manager_.obj());
-  j_audio_manager_.Reset();
+  initialized_ = true;
 }
 
 bool AudioManagerAndroid::HasAudioOutputDevices() {
   return true;
 }
 
 bool AudioManagerAndroid::HasAudioInputDevices() {
   return true;
 }
 
@@ skipping 331 matching lines @@
   output_volume_override_ = volume;
 
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   for (OutputStreams::iterator it = streams_.begin();
        it != streams_.end(); ++it) {
     (*it)->SetVolume(volume);
   }
 }
 
 }  // namespace media