Use fake clock in some more networks tests.

webrtc/base/fakeclock.h

Index: webrtc/base/fakeclock.h
diff --git a/webrtc/base/fakeclock.h b/webrtc/base/fakeclock.h
index eb78cf864de57b6267948c0c4e7dc83fc3ac0d13..fcdfc0bc2575fc24e5a37213ee0e64cd4ecf463f 100644
--- a/webrtc/base/fakeclock.h
+++ b/webrtc/base/fakeclock.h
@@ -56,6 +56,16 @@ class ScopedFakeClock : public FakeClock {
   ClockInterface* prev_clock_;
 };
 
+// Helper class to "undo" the fake clock temporarily.
+class ScopedRealClock {
+ public:
+  ScopedRealClock();
+  ~ScopedRealClock();
+
+ private:
+  ClockInterface* prev_clock_;
+};
+
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_FAKECLOCK_H_