Wire up uma histograms with webrtc.

third_party/libjingle/overrides/init_webrtc.h

Index: third_party/libjingle/overrides/init_webrtc.h
diff --git a/third_party/libjingle/overrides/init_webrtc.h b/third_party/libjingle/overrides/init_webrtc.h
index c5c190c3350929e17d7daa688fd9bf7d5ef85e55..2dc611905ec6286c943bef3def62dfe14fdad455 100644
--- a/third_party/libjingle/overrides/init_webrtc.h
+++ b/third_party/libjingle/overrides/init_webrtc.h
@@ -23,10 +23,22 @@ class WebRtcVideoEncoderFactory;
 
 namespace webrtc {
 class AudioDeviceModule;
+namespace metrics {
+class Histogram;
+}  // namespace metrics
 }  // namespace webrtc
 
 typedef std::string (*FieldTrialFindFullName)(const std::string& trial_name);
 
+typedef webrtc::metrics::Histogram* (*RtcHistogramFactoryGetCounts)(
+    const std::string& name, int min, int max, int bucket_count);
+typedef webrtc::metrics::Histogram* (*RtcHistogramFactoryGetEnumeration)(
+    const std::string& name, int boundary);
+typedef void (*RtcHistogramAdd)(
+    webrtc::metrics::Histogram* histogram_pointer,
+    const std::string& name,
+    int sample);
+
 typedef cricket::MediaEngineInterface* (*CreateWebRtcMediaEngineFunction)(
     webrtc::AudioDeviceModule* adm,
     webrtc::AudioDeviceModule* adm_sc,
@@ -51,6 +63,9 @@ typedef bool (*InitializeModuleFunction)(
     DellocateFunction dealloc,
 #endif
     FieldTrialFindFullName field_trial_find,
+    RtcHistogramFactoryGetCounts factory_get_counts,
+    RtcHistogramFactoryGetEnumeration factory_get_enumeration,
+    RtcHistogramAdd histogram_add,
     logging::LogMessageHandlerFunction log_handler,
     webrtc::GetCategoryEnabledPtr trace_get_category_enabled,
     webrtc::AddTraceEventPtr trace_add_trace_event,