Obj-C SDK Cleanup

This CL separates the files under sdk/objc into logical directories, replacing
the previous file layout under Framework/.

A long term goal is to have some system set up to generate the files under
sdk/objc/api (the PeerConnection API wrappers) from the C++ code. In the shorter
term the goal is to abstract out shared concepts from these classes in order to
make them as uniform as possible.

The separation into base/, components/, and helpers/ are to differentiate between
the base layer's common protocols, various utilities and the actual platform
specific components.

The old directory layout that resembled a framework's internal layout is not
necessary, since it is generated by the framework target when building it.

Bug: webrtc:9627
Change-Id: Ib084fd83f050ae980649ca99e841f4fb0580bd8f
Reviewed-on: https://webrtc-review.googlesource.com/94142
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24493}
diff --git a/sdk/objc/components/renderer/metal/RTCMTLVideoView.h b/sdk/objc/components/renderer/metal/RTCMTLVideoView.h
new file mode 100644
index 0000000..ff64ba3
--- /dev/null
+++ b/sdk/objc/components/renderer/metal/RTCMTLVideoView.h
@@ -0,0 +1,46 @@
+/*
+ *  Copyright 2017 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 <Foundation/Foundation.h>
+
+#import "RTCMacros.h"
+#import "RTCVideoFrame.h"
+#import "RTCVideoRenderer.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * RTCMTLVideoView is thin wrapper around MTKView.
+ *
+ * It has id<RTCVideoRenderer> property that renders video frames in the view's
+ * bounds using Metal.
+ * NOTE: always check if metal is available on the running device via
+ * RTC_SUPPORTS_METAL macro before initializing this class.
+ */
+NS_CLASS_AVAILABLE_IOS(9)
+
+RTC_EXPORT
+@interface RTCMTLVideoView : UIView<RTCVideoRenderer>
+
+@property(nonatomic, weak) id<RTCVideoViewDelegate> delegate;
+
+@property(nonatomic) UIViewContentMode videoContentMode;
+
+/** @abstract Enables/disables rendering.
+ */
+@property(nonatomic, getter=isEnabled) BOOL enabled;
+
+/** @abstract Wrapped RTCVideoRotation, or nil.
+ */
+@property(nonatomic, nullable) NSValue* rotationOverride;
+
+@end
+
+NS_ASSUME_NONNULL_END