Make UMA stats creation available in the Java interface.

webrtc/system_wrappers/source/metrics_default.cc

 // Copyright (c) 2014 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.
 //
 
 #include "webrtc/system_wrappers/include/metrics_default.h"
@@ skipping 226 matching lines @@
                   const std::string& name,
                   int sample) {
   if (!histogram_pointer)
     return;
 
   RtcHistogram* ptr = reinterpret_cast<RtcHistogram*>(histogram_pointer);
   RTC_DCHECK_EQ(name, ptr->name()) << "The name should not vary.";
   ptr->Add(sample);
 }
 
+// Fast path. Adds |sample| to cached |histogram_pointer|.
+void HistogramAdd(Histogram* histogram_pointer, int sample) {
+  if (!histogram_pointer)
+    return;
+
+  RtcHistogram* ptr = reinterpret_cast<RtcHistogram*>(histogram_pointer);
+  ptr->Add(sample);
+}
+
 SampleInfo::SampleInfo(const std::string& name,
                        int min,
                        int max,
                        size_t bucket_count)
     : name(name), min(min), max(max), bucket_count(bucket_count) {}
 
 SampleInfo::~SampleInfo() {}
 
 // Implementation of global functions in metrics_default.h.
 void Enable() {
@@ skipping 28 matching lines @@
   return map ? map->NumSamples(name) : 0;
 }
 
 int MinSample(const std::string& name) {
   RtcHistogramMap* map = GetMap();
   return map ? map->MinSample(name) : -1;
 }
 
 }  // namespace metrics
 }  // namespace webrtc