Build dynamic iOS SDK.

- Places most ObjC code into webrtc/sdk/objc instead.
- New gyp targets to build, strip and export symbols for dylib.
- Removes old script used to generate dylib.

BUG=

Review URL: https://codereview.webrtc.org/1903663002

Cr-Commit-Position: refs/heads/master@{#12524}
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCCameraPreviewView.m b/webrtc/sdk/objc/Framework/Classes/RTCCameraPreviewView.m
new file mode 100644
index 0000000..659973f
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Classes/RTCCameraPreviewView.m
@@ -0,0 +1,43 @@
+/*
+ *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "WebRTC/RTCCameraPreviewView.h"
+
+#import <AVFoundation/AVFoundation.h>
+
+#import "RTCDispatcher+Private.h"
+
+@implementation RTCCameraPreviewView
+
+@synthesize captureSession = _captureSession;
+
++ (Class)layerClass {
+  return [AVCaptureVideoPreviewLayer class];
+}
+
+- (void)setCaptureSession:(AVCaptureSession *)captureSession {
+  if (_captureSession == captureSession) {
+    return;
+  }
+  _captureSession = captureSession;
+  AVCaptureVideoPreviewLayer *previewLayer = [self previewLayer];
+  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
+                               block:^{
+    previewLayer.session = captureSession;
+  }];
+}
+
+#pragma mark - Private
+
+- (AVCaptureVideoPreviewLayer *)previewLayer {
+  return (AVCaptureVideoPreviewLayer *)self.layer;
+}
+
+@end