Adds support for Bluetooth headsets to the iOS audio layer

webrtc/modules/utility/interface/helpers_ios.h

Index: webrtc/modules/utility/interface/helpers_ios.h
diff --git a/webrtc/modules/utility/interface/helpers_ios.h b/webrtc/modules/utility/interface/helpers_ios.h
index 1e6075faae98bf5727e1c8f9864caf01c697a831..a5edee0279575f7f9b110e72aa37fa3b6c208547 100644
--- a/webrtc/modules/utility/interface/helpers_ios.h
+++ b/webrtc/modules/utility/interface/helpers_ios.h
@@ -20,6 +20,8 @@ namespace ios {
 
 bool CheckAndLogError(BOOL success, NSError* error);
 
+std::string StdStringFromNSString(NSString* nsString);
+
 // Return thread ID as a string.
 std::string GetThreadId();
 
@@ -30,6 +32,8 @@ std::string GetThreadInfo();
 // Example: <NSThread: 0x170066d80>{number = 1, name = main}
 std::string GetCurrentThreadDescription();
 
+std::string GetAudioSessionCategory();
+
 // Returns the current name of the operating system.
 std::string GetSystemName();