Make sure StatisticsRecorder::Initialize() is called at initialization

components/cronet/ios/cronet_environment.mm

Index: components/cronet/ios/cronet_environment.mm
diff --git a/components/cronet/ios/cronet_environment.mm b/components/cronet/ios/cronet_environment.mm
index 246ead1984b7e2dbbee6840dddea31626063ce89..b9d36033029076f79029ba6e18313fe2a8dae7ba 100644
--- a/components/cronet/ios/cronet_environment.mm
+++ b/components/cronet/ios/cronet_environment.mm
@@ -112,8 +112,8 @@ net::URLRequestContextGetter* CronetEnvironment::GetURLRequestContextGetter()
 
 // static
 void CronetEnvironment::Initialize() {
-  // DCHECK_EQ([NSThread currentThread], [NSThread mainThread]);
   // This method must be called once from the main thread.
+  DCHECK_EQ([NSThread currentThread], [NSThread mainThread]);
   if (!g_at_exit_)
     g_at_exit_ = new base::AtExitManager;
 
@@ -350,7 +350,7 @@ std::string CronetEnvironment::user_agent() {
 }
 
 std::vector<uint8_t> CronetEnvironment::GetHistogramDeltas() {
-  base::StatisticsRecorder::Initialize();
+  DCHECK(base::StatisticsRecorder::IsActive());
   std::vector<uint8_t> data;
   if (!HistogramManager::GetInstance()->GetDeltas(&data))
     return std::vector<uint8_t>();