Patch for WebRTC M84 to not prompt mic permissions for "viewers" of a WebRTC call on iOS

m84+mic-permissions.patch

diff --git a/sdk/objc/components/audio/RTCAudioSessionConfiguration.m b/sdk/objc/components/audio/RTCAudioSessionConfiguration.m
index 39e9ac13ec..a11a0037cd 100644
--- a/sdk/objc/components/audio/RTCAudioSessionConfiguration.m
+++ b/sdk/objc/components/audio/RTCAudioSessionConfiguration.m
@@ -65,15 +65,16 @@ static RTC_OBJC_TYPE(RTCAudioSessionConfiguration) *gWebRTCConfiguration = nil;
 
 - (instancetype)init {
   if (self = [super init]) {
+    AVAudioSession *session = [AVAudioSession sharedInstance];
     // Use a category which supports simultaneous recording and playback.
     // By default, using this category implies that our app’s audio is
     // nonmixable, hence activating the session will interrupt any other
-    // audio sessions which are also nonmixable.
-    _category = AVAudioSessionCategoryPlayAndRecord;
-    _categoryOptions = AVAudioSessionCategoryOptionAllowBluetooth;
+    // audio sessions which are also nonmixable.    
+    _category = session.category;
+    _categoryOptions = session.categoryOptions;
 
     // Specify mode for two-way voice communication (e.g. VoIP).
-    _mode = AVAudioSessionModeVoiceChat;
+    _mode = session.mode;
 
     // Set the session's sample rate or the hardware sample rate.
     // It is essential that we use the same sample rate as stream format
diff --git a/sdk/objc/native/src/audio/voice_processing_audio_unit.mm b/sdk/objc/native/src/audio/voice_processing_audio_unit.mm
index a2aa7f323b..52aac4f315 100644
--- a/sdk/objc/native/src/audio/voice_processing_audio_unit.mm
+++ b/sdk/objc/native/src/audio/voice_processing_audio_unit.mm
@@ -110,16 +110,22 @@ bool VoiceProcessingAudioUnit::Init() {
   }
 
   // Enable input on the input scope of the input element.
-  UInt32 enable_input = 1;
-  result = AudioUnitSetProperty(vpio_unit_, kAudioOutputUnitProperty_EnableIO,
-                                kAudioUnitScope_Input, kInputBus, &enable_input,
-                                sizeof(enable_input));
-  if (result != noErr) {
-    DisposeAudioUnit();
-    RTCLogError(@"Failed to enable input on input scope of input element. "
-                 "Error=%ld.",
-                (long)result);
-    return false;
+  AVAudioSession *session = [AVAudioSession sharedInstance];
+  if (session.category == AVAudioSessionCategoryPlayAndRecord) {
+    UInt32 enable_input = 1;
+    result = AudioUnitSetProperty(vpio_unit_, kAudioOutputUnitProperty_EnableIO,
+                                  kAudioUnitScope_Input, kInputBus, &enable_input,
+                                  sizeof(enable_input));
+    if (result != noErr) {
+      DisposeAudioUnit();
+      RTCLogError(@"Failed to enable input on input scope of input element. "
+                  "Error=%ld.",
+                  (long)result);
+      return false;
+    }
+  }
+  else {
+    RTCLog("@Not Enable input on the input scope of the input element.");
   }
 
   // Enable output on the output scope of the output element.
@@ -153,34 +159,44 @@ bool VoiceProcessingAudioUnit::Init() {
 
   // Disable AU buffer allocation for the recorder, we allocate our own.
   // TODO(henrika): not sure that it actually saves resource to make this call.
-  UInt32 flag = 0;
-  result = AudioUnitSetProperty(
-      vpio_unit_, kAudioUnitProperty_ShouldAllocateBuffer,
-      kAudioUnitScope_Output, kInputBus, &flag, sizeof(flag));
-  if (result != noErr) {
-    DisposeAudioUnit();
-    RTCLogError(@"Failed to disable buffer allocation on the input bus. "
-                 "Error=%ld.",
-                (long)result);
-    return false;
+  if (session.category == AVAudioSessionCategoryPlayAndRecord) {
+    UInt32 flag = 0;
+    result = AudioUnitSetProperty(
+        vpio_unit_, kAudioUnitProperty_ShouldAllocateBuffer,
+        kAudioUnitScope_Output, kInputBus, &flag, sizeof(flag));
+    if (result != noErr) {
+      DisposeAudioUnit();
+      RTCLogError(@"Failed to disable buffer allocation on the input bus. "
+                  "Error=%ld.",
+                  (long)result);
+      return false;
+    }
+  }
+  else {
+    RTCLog("@NOT Disable AU buffer allocation for the recorder, we allocate our own.");
   }
 
   // Specify the callback to be called by the I/O thread to us when input audio
   // is available. The recorded samples can then be obtained by calling the
   // AudioUnitRender() method.
-  AURenderCallbackStruct input_callback;
-  input_callback.inputProc = OnDeliverRecordedData;
-  input_callback.inputProcRefCon = this;
-  result = AudioUnitSetProperty(vpio_unit_,
-                                kAudioOutputUnitProperty_SetInputCallback,
-                                kAudioUnitScope_Global, kInputBus,
-                                &input_callback, sizeof(input_callback));
-  if (result != noErr) {
-    DisposeAudioUnit();
-    RTCLogError(@"Failed to specify the input callback on the input bus. "
-                 "Error=%ld.",
-                (long)result);
-    return false;
+  if (session.category == AVAudioSessionCategoryPlayAndRecord) {
+    AURenderCallbackStruct input_callback;
+    input_callback.inputProc = OnDeliverRecordedData;
+    input_callback.inputProcRefCon = this;
+    result = AudioUnitSetProperty(vpio_unit_,
+                                  kAudioOutputUnitProperty_SetInputCallback,
+                                  kAudioUnitScope_Global, kInputBus,
+                                  &input_callback, sizeof(input_callback));
+    if (result != noErr) {
+      DisposeAudioUnit();
+      RTCLogError(@"Failed to specify the input callback on the input bus. "
+                  "Error=%ld.",
+                  (long)result);
+      return false;
+    }
+  }
+  else {
+    RTCLog("@NOT Specify the callback to be called by the I/O thread to us when input audio");
   }
 
   state_ = kUninitialized;
@@ -203,14 +219,20 @@ bool VoiceProcessingAudioUnit::Initialize(Float64 sample_rate) {
 #endif
 
   // Set the format on the output scope of the input element/bus.
-  result =
-      AudioUnitSetProperty(vpio_unit_, kAudioUnitProperty_StreamFormat,
-                           kAudioUnitScope_Output, kInputBus, &format, size);
-  if (result != noErr) {
-    RTCLogError(@"Failed to set format on output scope of input bus. "
-                 "Error=%ld.",
-                (long)result);
-    return false;
+  AVAudioSession *session = [AVAudioSession sharedInstance];
+  if (session.category == AVAudioSessionCategoryPlayAndRecord) {
+    result =
+        AudioUnitSetProperty(vpio_unit_, kAudioUnitProperty_StreamFormat,
+                            kAudioUnitScope_Output, kInputBus, &format, size);
+    if (result != noErr) {
+      RTCLogError(@"Failed to set format on output scope of input bus. "
+                  "Error=%ld.",
+                  (long)result);
+      return false;
+    }
+  }
+  else {
+    RTCLog("@NOT setting the format on the output sscope of the input element because it's movie mode");
   }
 
   // Set the format on the input scope of the output element/bus.