Add MODIFY_AUDIO_SETTINGS permission in Android manifest and implementation in audio manager.

media/audio/android/opensles_output.cc

Index: media/audio/android/opensles_output.cc
===================================================================
--- media/audio/android/opensles_output.cc	(revision 186971)
+++ media/audio/android/opensles_output.cc	(working copy)
@@ -49,6 +49,46 @@
   DCHECK(!audio_data_[0]);
 }
 
+void OpenSLESOutputStream::SetAudioMode() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  jobject j_context = base::android::GetApplicationContext();
+  DCHECK(j_context);
+
+  // context.getSystemService(Context.AUDIO_SERVICE).

[Yaron, 2013/03/09 00:31:18]

We're no longer taking patches with hand-written JNI bindings. Please use the
jni_generator. In this case, you can create a smaller wrapper class that you can
call into, passing it the application context and have it make the appropriate
java calls. See https://codereview.chromium.org/12604003/ for reference.

+  jstring audio_service_string = env->NewStringUTF("audio");
+  jclass context_class = env->GetObjectClass(j_context);

[Yaron, 2013/03/09 00:31:18]

Examle for why we say this: you're currently leaking this jclass. If you make
enough calls of this nature, dalvik will kill our process with a deadd00d
assertion which gives you no information about where the issue is without
logcat.

+  CHECK(context_class);
+  jmethodID method = env->GetMethodID(
+      context_class, "getSystemService",
+      "(Ljava/lang/String;)Ljava/lang/Object;");
+  CHECK(method);
+  jobject j_am = env->CallObjectMethod(j_context, method,
+                                       audio_service_string);
+  CHECK(j_am);
+  jclass j_am_class = env->GetObjectClass(j_am);
+  CHECK(j_am_class);
+
+  // AudioManager.MODE_IN_COMMUNICATION.
+  jclass cls = env->FindClass("android/media/AudioManager");
+  CHECK(cls);
+  jfieldID field = env->GetStaticFieldID(
+      cls,
+      "MODE_IN_COMMUNICATION",
+      "I");
+  CHECK(field);
+  jint am_mode = env->GetStaticIntField(cls, field);
+  CHECK(am_mode);
+  env->DeleteLocalRef(cls);
+
+  // audioManager.setMode(AudioManager.MODE_IN_COMMUNICATION)
+  jmethodID setmode_method = env->GetMethodID(j_am_class, "setMode", "(I)V");
+  CHECK(setmode_method);
+  env->CallVoidMethod(j_am, setmode_method, am_mode);
+  base::android::CheckException(env);
+}
+
 bool OpenSLESOutputStream::Open() {
   if (engine_object_.Get())
     return false;
@@ -56,6 +96,8 @@
   if (!CreatePlayer())
     return false;
 
+  SetAudioMode();
+
   SetupAudioBuffer();
 
   return true;