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 47 matching lines @@
     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) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
-
-  // 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
-  // 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();
 
+  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() {
+  GetTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(base::Bind(base::IgnoreResult(
+                                &AudioManagerAndroid::GetJavaAudioManager)),
+                            base::Unretained(this)));
+}
+
 bool AudioManagerAndroid::HasAudioOutputDevices() {
   return true;
 }
 
 bool AudioManagerAndroid::HasAudioInputDevices() {
   return true;
 }
 
 void AudioManagerAndroid::GetAudioInputDeviceNames(
     AudioDeviceNames* device_names) {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
 
   // Always add default device parameters as first element.
   DCHECK(device_names->empty());
   AddDefaultDevice(device_names);
 
   // Get list of available audio devices.
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobjectArray> j_device_array =
-      Java_AudioManagerAndroid_getAudioInputDeviceNames(
-          env, j_audio_manager_.obj());
+      Java_AudioManagerAndroid_getAudioInputDeviceNames(env,
+                                                        GetJavaAudioManager());
   if (j_device_array.is_null()) {
     // Most probable reason for a NULL result here is that the process lacks
     // MODIFY_AUDIO_SETTINGS or RECORD_AUDIO permissions.
     return;
   }
   jsize len = env->GetArrayLength(j_device_array.obj());
   AudioDeviceName device;
   for (jsize i = 0; i < len; ++i) {
     ScopedJavaLocalRef<jobject> j_device(
         env, env->GetObjectArrayElement(j_device_array.obj(), i));
@@ skipping 72 matching lines @@
 }
 
 void AudioManagerAndroid::ReleaseOutputStream(AudioOutputStream* stream) {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   streams_.erase(static_cast<OpenSLESOutputStream*>(stream));
   AudioManagerBase::ReleaseOutputStream(stream);
 }
 
 void AudioManagerAndroid::ReleaseInputStream(AudioInputStream* stream) {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  DCHECK(!j_audio_manager_.is_null());
   AudioManagerBase::ReleaseInputStream(stream);
 
   // Restore the audio mode which was used before the first communication-
   // mode stream was created.
   if (HasNoAudioInputStreams()) {
     communication_mode_is_on_ = false;
     SetCommunicationAudioModeOn(false);
   }
 }
 
@@ skipping 128 matching lines @@
     buffer_size = user_buffer_size;
 
   return AudioParameters(AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
                          sample_rate, bits_per_sample, buffer_size);
 }
 
 bool AudioManagerAndroid::HasNoAudioInputStreams() {
   return input_stream_count() == 0;
 }
 
-void AudioManagerAndroid::InitializeOnAudioThread() {
+jobject AudioManagerAndroid::GetJavaAudioManager() {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  if (j_audio_manager_.is_null()) {
+    // Create the Android audio manager on the audio thread.
+    DVLOG(2) << "Creating Java part of the audio manager";
+    j_audio_manager_.Reset(Java_AudioManagerAndroid_createAudioManagerAndroid(
+        base::android::AttachCurrentThread(),
+        base::android::GetApplicationContext(),
+        reinterpret_cast<intptr_t>(this)));
 
-  // Create the Android audio manager on the audio thread.
-  DVLOG(2) << "Creating Java part of the audio manager";
-  j_audio_manager_.Reset(
-      Java_AudioManagerAndroid_createAudioManagerAndroid(
-          base::android::AttachCurrentThread(),
-          base::android::GetApplicationContext(),
-          reinterpret_cast<intptr_t>(this)));
-
-  // Prepare the list of audio devices and register receivers for device
-  // notifications.
-  Java_AudioManagerAndroid_init(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj());
+    // Prepare the list of audio devices and register receivers for device
+    // notifications.
+    Java_AudioManagerAndroid_init(base::android::AttachCurrentThread(),
+                                  j_audio_manager_.obj());
+  }
+  return j_audio_manager_.obj();
 }
 
 void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
   Java_AudioManagerAndroid_setCommunicationAudioModeOn(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj(), on);
+      base::android::AttachCurrentThread(), GetJavaAudioManager(), on);
 }
 
 bool AudioManagerAndroid::SetAudioDevice(const std::string& device_id) {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
 
   // Send the unique device ID to the Java audio manager and make the
   // device switch. Provide an empty string to the Java audio manager
   // if the default device is selected.
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jstring> j_device_id = ConvertUTF8ToJavaString(
       env, device_id == AudioDeviceDescription::kDefaultDeviceId ? std::string()
                                                                  : device_id);
-  return Java_AudioManagerAndroid_setDevice(
-      env, j_audio_manager_.obj(), j_device_id.obj());
+  return Java_AudioManagerAndroid_setDevice(env, GetJavaAudioManager(),
+                                            j_device_id.obj());
 }
 
 int AudioManagerAndroid::GetNativeOutputSampleRate() {
   return Java_AudioManagerAndroid_getNativeOutputSampleRate(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj());
+      base::android::AttachCurrentThread(), GetJavaAudioManager());
 }
 
 bool AudioManagerAndroid::IsAudioLowLatencySupported() {
   return Java_AudioManagerAndroid_isAudioLowLatencySupported(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj());
+      base::android::AttachCurrentThread(), GetJavaAudioManager());
 }
 
 int AudioManagerAndroid::GetAudioLowLatencyOutputFrameSize() {
   return Java_AudioManagerAndroid_getAudioLowLatencyOutputFrameSize(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj());
+      base::android::AttachCurrentThread(), GetJavaAudioManager());
 }
 
 int AudioManagerAndroid::GetOptimalOutputFrameSize(int sample_rate,
                                                    int channels) {
   if (IsAudioLowLatencySupported())
     return GetAudioLowLatencyOutputFrameSize();
 
   return std::max(kDefaultOutputBufferSize,
                   Java_AudioManagerAndroid_getMinOutputFrameSize(
                       base::android::AttachCurrentThread(),
@@ skipping 13 matching lines @@
   output_volume_override_ = volume;
 
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   for (OutputStreams::iterator it = streams_.begin();
        it != streams_.end(); ++it) {
     (*it)->SetVolume(volume);
   }
 }
 
 }  // namespace media