Add ObjC API for getting native histograms.

webrtc/sdk/objc/Framework/Classes/RTCMetricsSampleInfo+Private.h

 /*
  *  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 "AppDelegate.h"
-#import <WebRTC/WebRTC.h>
+#import "WebRTC/RTCMetricsSampleInfo.h"
 
-@implementation AppDelegate
+#include "webrtc/system_wrappers/include/metrics_default.h"
 
-- (BOOL)application:(UIApplication *)application
-    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-  RTCInitializeSSL();
-  return YES;
-}
+NS_ASSUME_NONNULL_BEGIN
 
-- (void)applicationWillTerminate:(UIApplication *)application {
-  RTCCleanupSSL();
-}
+@interface RTCMetricsSampleInfo ()
+
+/** Initialize an RTCMetricsSampleInfo object from native SampleInfo. */
+- (instancetype)initWithNativeSampleInfo:
+    (const webrtc::metrics::SampleInfo &)info;
 
 @end
+
+NS_ASSUME_NONNULL_END