Nuke TickTime::UseFakeClock.

Removes the global simulated time that affects (or breaks) following
tests in the same binary and replaces it with SimulatedClock.

BUG=webrtc:5318
R=mflodman@webrtc.org

Review URL: https://codereview.webrtc.org/1512853002 .

Cr-Commit-Position: refs/heads/master@{#10947}
diff --git a/webrtc/call/call.cc b/webrtc/call/call.cc
index f6efa6d..28f1315 100644
--- a/webrtc/call/call.cc
+++ b/webrtc/call/call.cc
@@ -117,7 +117,7 @@
   void UpdateSendHistograms() EXCLUSIVE_LOCKS_REQUIRED(&bitrate_crit_);
   void UpdateReceiveHistograms();
 
-  const Clock* const clock_;
+  Clock* const clock_;
 
   const int num_cpu_cores_;
   const rtc::scoped_ptr<ProcessThread> module_process_thread_;
@@ -182,7 +182,7 @@
     : clock_(Clock::GetRealTimeClock()),
       num_cpu_cores_(CpuInfo::DetectNumberOfCores()),
       module_process_thread_(ProcessThread::Create("ModuleProcessThread")),
-      call_stats_(new CallStats()),
+      call_stats_(new CallStats(clock_)),
       bitrate_allocator_(new BitrateAllocator()),
       config_(config),
       network_enabled_(true),