Fix lock behavior on RTCAudioSession.

In addition:
- Introduces RTCAudioSessionTest
- iOS/Mac gtests now have an autoreleasepool
- Moves ScopedAutoreleasePool to rtc_base_approved
- Introduces route change button in AppRTCDemo

BUG=webrtc:5649

Review URL: https://codereview.webrtc.org/1782363002

Cr-Commit-Position: refs/heads/master@{#11971}
diff --git a/webrtc/webrtc_examples.gyp b/webrtc/webrtc_examples.gyp
index 279382c..e08176a 100755
--- a/webrtc/webrtc_examples.gyp
+++ b/webrtc/webrtc_examples.gyp
@@ -281,14 +281,16 @@
           'conditions': [
             ['OS=="ios"', {
               'mac_bundle_resources': [
+                'examples/objc/AppRTCDemo/ios/resources/Roboto-Regular.ttf',
                 'examples/objc/AppRTCDemo/ios/resources/iPhone5@2x.png',
                 'examples/objc/AppRTCDemo/ios/resources/iPhone6@2x.png',
                 'examples/objc/AppRTCDemo/ios/resources/iPhone6p@3x.png',
-                'examples/objc/AppRTCDemo/ios/resources/Roboto-Regular.ttf',
                 'examples/objc/AppRTCDemo/ios/resources/ic_call_end_black_24dp.png',
                 'examples/objc/AppRTCDemo/ios/resources/ic_call_end_black_24dp@2x.png',
                 'examples/objc/AppRTCDemo/ios/resources/ic_clear_black_24dp.png',
                 'examples/objc/AppRTCDemo/ios/resources/ic_clear_black_24dp@2x.png',
+                'examples/objc/AppRTCDemo/ios/resources/ic_surround_sound_black_24dp.png',
+                'examples/objc/AppRTCDemo/ios/resources/ic_surround_sound_black_24dp@2x.png',
                 'examples/objc/AppRTCDemo/ios/resources/ic_switch_video_black_24dp.png',
                 'examples/objc/AppRTCDemo/ios/resources/ic_switch_video_black_24dp@2x.png',
                 'examples/objc/AppRTCDemo/ios/resources/mozart.mp3',