Reland of Split iOS sdk in to separate targets (patchset #1 id:1 of https://codereview.webrtc.org/2890513002/ )

Reason for revert:
Fixing downstream breakages

Original issue's description:
> Revert of Split iOS sdk in to separate targets (patchset #13 id:280001 of https://codereview.webrtc.org/2862543002/ )
>
> Reason for revert:
> Breaking downstream projects.
>
> Original issue's description:
> > Split iOS sdk in to separate targets
> >
> > This CL splits the iOS sdk into separate static libraries for video,
> > audio, ui, common, and peerconnection-related code. This will in the
> > future make it easier to compile WebRTC without unneeded components.
> >
> > BUG=webrtc:4867
> >
> > Review-Url: https://codereview.webrtc.org/2862543002
> > Cr-Commit-Position: refs/heads/master@{#18166}
> > Committed: 52c83fe710
>
> TBR=magjed@webrtc.org,denicija@webrtc.org,tkchin@webrtc.org,henrika@webrtc.org,kthelgason@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:4867
>
> Review-Url: https://codereview.webrtc.org/2890513002
> Cr-Commit-Position: refs/heads/master@{#18170}
> Committed: 9756238084

TBR=magjed@webrtc.org,denicija@webrtc.org,tkchin@webrtc.org,henrika@webrtc.org,charujain@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:4867

Review-Url: https://codereview.webrtc.org/2890733003
Cr-Commit-Position: refs/heads/master@{#18174}

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCVideoRendererAdapter.mm

@@ -0,0 +1,70 @@
+/*
+ *  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 "RTCVideoRendererAdapter+Private.h"
+
+#import "RTCVideoFrame+Private.h"
+
+#include <memory>
+
+namespace webrtc {
+
+class VideoRendererAdapter
+    : public rtc::VideoSinkInterface<webrtc::VideoFrame> {
+ public:
+  VideoRendererAdapter(RTCVideoRendererAdapter* adapter) {
+    adapter_ = adapter;
+    size_ = CGSizeZero;
+  }
+
+  void OnFrame(const webrtc::VideoFrame& nativeVideoFrame) override {
+    RTCVideoFrame* videoFrame = [[RTCVideoFrame alloc]
+        initWithVideoBuffer:nativeVideoFrame.video_frame_buffer()
+                   rotation:static_cast<RTCVideoRotation>(
+                                nativeVideoFrame.rotation())
+                timeStampNs:nativeVideoFrame.timestamp_us() *
+                            rtc::kNumNanosecsPerMicrosec];
+    CGSize current_size = (videoFrame.rotation % 180 == 0)
+                              ? CGSizeMake(videoFrame.width, videoFrame.height)
+                              : CGSizeMake(videoFrame.height, videoFrame.width);
+
+    if (!CGSizeEqualToSize(size_, current_size)) {
+      size_ = current_size;
+      [adapter_.videoRenderer setSize:size_];
+    }
+    [adapter_.videoRenderer renderFrame:videoFrame];
+  }
+
+ private:
+  __weak RTCVideoRendererAdapter *adapter_;
+  CGSize size_;
+};
+}
+
+@implementation RTCVideoRendererAdapter {
+  std::unique_ptr<webrtc::VideoRendererAdapter> _adapter;
+}
+
+@synthesize videoRenderer = _videoRenderer;
+
+- (instancetype)initWithNativeRenderer:(id<RTCVideoRenderer>)videoRenderer {
+  NSParameterAssert(videoRenderer);
+  if (self = [super init]) {
+    _videoRenderer = videoRenderer;
+    _adapter.reset(new webrtc::VideoRendererAdapter(self));
+  }
+  return self;
+}
+
+- (rtc::VideoSinkInterface<webrtc::VideoFrame> *)nativeVideoRenderer {
+  return _adapter.get();
+}
+
+@end