Add UMA metrics for ICE regathering reasons.

webrtc/p2p/base/portallocator.h

Index: webrtc/p2p/base/portallocator.h
diff --git a/webrtc/p2p/base/portallocator.h b/webrtc/p2p/base/portallocator.h
index 8befbadcc73981375d22ba23b321c417fbb2cd21..3c81068060a3a717f94e329db7ed541dc86c9e51 100644
--- a/webrtc/p2p/base/portallocator.h
+++ b/webrtc/p2p/base/portallocator.h
@@ -23,6 +23,10 @@
 #include "webrtc/base/sigslot.h"
 #include "webrtc/base/thread.h"
 
+namespace webrtc {
+class MetricsObserverInterface;
+}
+
 namespace cricket {
 
 // PortAllocator is responsible for allocating Port types for a given
@@ -72,6 +76,9 @@ enum {
   PORTALLOCATOR_DISABLE_COSTLY_NETWORKS = 0x2000,
 };
 
+// Defines various reasons that have caused ICE regathering.
+enum class IceRegatheringReason { NETWORK_CHANGE, NETWORK_FAILURE, MAX_VALUE };
+
 const uint32_t kDefaultPortAllocatorFlags = 0;
 
 const uint32_t kDefaultStepDelay = 1000;  // 1 sec step delay.
@@ -216,6 +223,9 @@ class PortAllocatorSession : public sigslot::has_slots<> {
       SignalCandidatesRemoved;
   sigslot::signal1<PortAllocatorSession*> SignalCandidatesAllocationDone;
 
+  sigslot::signal2<PortAllocatorSession*, IceRegatheringReason>
+      SignalIceRegathering;
+
   virtual uint32_t generation() { return generation_; }
   virtual void set_generation(uint32_t generation) { generation_ = generation; }
   sigslot::signal1<PortAllocatorSession*> SignalDestroyed;
@@ -370,6 +380,10 @@ class PortAllocator : public sigslot::has_slots<> {
   const std::string& origin() const { return origin_; }
   void set_origin(const std::string& origin) { origin_ = origin; }
 
+  void SetMetricsObserver(webrtc::MetricsObserverInterface* observer) {
+    metrics_observer_ = observer;
+  }
+
  protected:
   virtual PortAllocatorSession* CreateSessionInternal(
       const std::string& content_name,
@@ -377,6 +391,14 @@ class PortAllocator : public sigslot::has_slots<> {
       const std::string& ice_ufrag,
       const std::string& ice_pwd) = 0;
 
+  webrtc::MetricsObserverInterface* metrics_observer() {
+    return metrics_observer_;
+  }
+
+  const std::deque<std::unique_ptr<PortAllocatorSession>>& pooled_sessions() {
+    return pooled_sessions_;
+  }
+
   uint32_t flags_;
   std::string agent_;
   rtc::ProxyInfo proxy_;
@@ -397,6 +419,8 @@ class PortAllocator : public sigslot::has_slots<> {
   int allocated_pooled_session_count_ = 0;
   std::deque<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
   bool prune_turn_ports_ = false;
+
+  webrtc::MetricsObserverInterface* metrics_observer_ = nullptr;
 };
 
 }  // namespace cricket