Add file capturer to AppRTCMobile on simulator.

To achieve this, the CL does the following
- Adds sample mp4 video
- Refactors the existing RTCFileVideoCapturer to achieve continious
capture and adds tests.

Bug: webrtc:8406
Change-Id: Ibc0891176c58ec9053b42e340d2113036e7199ec
Reviewed-on: https://webrtc-review.googlesource.com/12180
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Daniela Jovanoska Petrenko <denicija@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20598}
diff --git a/examples/objc/AppRTCMobile/ARDSettingsModel.m b/examples/objc/AppRTCMobile/ARDSettingsModel.m
index 0a2bee6..a4eea73 100644
--- a/examples/objc/AppRTCMobile/ARDSettingsModel.m
+++ b/examples/objc/AppRTCMobile/ARDSettingsModel.m
@@ -169,20 +169,12 @@
 
 - (void)registerStoreDefaults {
   NSString *defaultVideoResolutionSetting = [self defaultVideoResolutionSetting];
-  BOOL audioOnly = (defaultVideoResolutionSetting.length == 0);
-
-// The iOS simulator doesn't provide any sort of camera capture
-// support or emulation (http://goo.gl/rHAnC1) so don't bother
-// trying to open a local stream.
-#if TARGET_IPHONE_SIMULATOR
-  audioOnly = YES;
-#endif
 
   NSData *codecData = [NSKeyedArchiver archivedDataWithRootObject:[self defaultVideoCodecSetting]];
   [ARDSettingsStore setDefaultsForVideoResolution:[self defaultVideoResolutionSetting]
                                        videoCodec:codecData
                                           bitrate:nil
-                                        audioOnly:audioOnly
+                                        audioOnly:NO
                                     createAecDump:NO
                                useLevelController:NO
                              useManualAudioConfig:YES];