iOS: Add ability to specify audio constraints.

NOTRY=True
BUG=

Review-Url: https://codereview.webrtc.org/2290583003
Cr-Commit-Position: refs/heads/master@{#13976}

webrtc/sdk/objc/Framework/Classes/RTCMediaSource.mm

@@ -0,0 +1,79 @@
+/*
+ *  Copyright 2016 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 "RTCMediaSource+Private.h"
+
+#include "webrtc/base/checks.h"
+
+@implementation RTCMediaSource {
+  RTCMediaSourceType _type;
+}
+
+@synthesize nativeMediaSource = _nativeMediaSource;
+
+- (instancetype)initWithNativeMediaSource:
+   (rtc::scoped_refptr<webrtc::MediaSourceInterface>)nativeMediaSource
+                                     type:(RTCMediaSourceType)type {
+  RTC_DCHECK(nativeMediaSource);
+  if (self = [super init]) {
+    _nativeMediaSource = nativeMediaSource;
+    _type = type;
+  }
+  return self;
+}
+
+- (RTCSourceState)state {
+  return [[self class] sourceStateForNativeState:_nativeMediaSource->state()];
+}
+
+#pragma mark - Private
+
++ (webrtc::MediaSourceInterface::SourceState)nativeSourceStateForState:
+    (RTCSourceState)state {
+  switch (state) {
+    case RTCSourceStateInitializing:
+      return webrtc::MediaSourceInterface::kInitializing;
+    case RTCSourceStateLive:
+      return webrtc::MediaSourceInterface::kLive;
+    case RTCSourceStateEnded:
+      return webrtc::MediaSourceInterface::kEnded;
+    case RTCSourceStateMuted:
+      return webrtc::MediaSourceInterface::kMuted;
+  }
+}
+
++ (RTCSourceState)sourceStateForNativeState:
+    (webrtc::MediaSourceInterface::SourceState)nativeState {
+  switch (nativeState) {
+    case webrtc::MediaSourceInterface::kInitializing:
+      return RTCSourceStateInitializing;
+    case webrtc::MediaSourceInterface::kLive:
+      return RTCSourceStateLive;
+    case webrtc::MediaSourceInterface::kEnded:
+      return RTCSourceStateEnded;
+    case webrtc::MediaSourceInterface::kMuted:
+      return RTCSourceStateMuted;
+  }
+}
+
++ (NSString *)stringForState:(RTCSourceState)state {
+  switch (state) {
+    case RTCSourceStateInitializing:
+      return @"Initializing";
+    case RTCSourceStateLive:
+      return @"Live";
+    case RTCSourceStateEnded:
+      return @"Ended";
+    case RTCSourceStateMuted:
+      return @"Muted";
+  }
+}
+
+@end