Revert "Add file capturer to AppRTCMobile on simulator."

This reverts commit 5adcd198752b651f7b7e9199a91f9b873b7d7237.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> 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}

TBR=magjed@webrtc.org,andersc@webrtc.org,denicija@webrtc.org

Change-Id: I73b35c67296c964f65d206454ac1329b4b979628
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8406
Reviewed-on: https://webrtc-review.googlesource.com/21240
Reviewed-by: Daniela Jovanoska Petrenko <denicija@webrtc.org>
Commit-Queue: Daniela Jovanoska Petrenko <denicija@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20599}
diff --git a/examples/objc/AppRTCMobile/ARDAppClient.h b/examples/objc/AppRTCMobile/ARDAppClient.h
index 5054c28..8c27b34 100644
--- a/examples/objc/AppRTCMobile/ARDAppClient.h
+++ b/examples/objc/AppRTCMobile/ARDAppClient.h
@@ -9,6 +9,8 @@
  */
 
 #import <Foundation/Foundation.h>
+
+#import "WebRTC/RTCCameraVideoCapturer.h"
 #import "WebRTC/RTCPeerConnection.h"
 #import "WebRTC/RTCVideoTrack.h"
 
@@ -24,8 +26,6 @@
 @class ARDAppClient;
 @class ARDSettingsModel;
 @class RTCMediaConstraints;
-@class RTCCameraVideoCapturer;
-@class RTCFileVideoCapturer;
 
 // The delegate is informed of pertinent events and will be called on the
 // main queue.
@@ -52,10 +52,6 @@
 - (void)appClient:(ARDAppClient *)client
       didGetStats:(NSArray *)stats;
 
-@optional
-- (void)appClient:(ARDAppClient *)client
-didCreateLocalFileCapturer:(RTCFileVideoCapturer *)fileCapturer;
-
 @end
 
 // Handles connections to the AppRTC server for a given room. Methods on this