Add ObjC API for getting native histograms.

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

Index: webrtc/sdk/objc/Framework/Classes/RTCMetrics.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCMetrics.mm b/webrtc/sdk/objc/Framework/Classes/RTCMetrics.mm
new file mode 100644
index 0000000000000000000000000000000000000000..446985d08598c089a0fdf493fddcfd42f853537e
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Classes/RTCMetrics.mm
@@ -0,0 +1,32 @@
+/*
+ *  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 "WebRTC/RTCMetrics.h"
+
+#import "RTCMetricsSampleInfo+Private.h"
+
+void RTCEnableMetrics() {
+  webrtc::metrics::Enable();
+}
+
+NSArray<RTCMetricsSampleInfo*>* RTCGetAndResetMetrics() {

[tkchin_webrtc, 2016/06/06 17:32:51]

NSArray<RTCMetricsSampleInfo *> *RTCGetAndResetMetrics()

don't do git cl format, it doesn't work well for ObjC++ and even for regular
ObjC does not comply with Google style

[åsapersson, 2016/06/07 06:10:25]

Done.

+  std::map<std::string, std::unique_ptr<webrtc::metrics::SampleInfo>>
+      histograms;
+  webrtc::metrics::GetAndReset(&histograms);
+
+  NSMutableArray* metrics =

[tkchin_webrtc, 2016/06/06 17:32:51]

NSMutableArray *metrics

[åsapersson, 2016/06/07 06:10:25]

Done.

+      [NSMutableArray arrayWithCapacity:histograms.size()];
+  for (auto const& histogram : histograms) {
+    RTCMetricsSampleInfo* metric = [[RTCMetricsSampleInfo alloc]

[tkchin_webrtc, 2016/06/06 17:32:51]

RTCMetricsSampleInfo *metric

[åsapersson, 2016/06/07 06:10:25]

Done.

+        initWithNativeSampleInfo:*histogram.second];
+    [metrics addObject:metric];
+  }
+  return metrics;
+}