Change rtc::TimeNanos and rtc::TimeMicros return value from uint64_t to int64_t.

webrtc/base/socket_unittest.cc

 /*
  *  Copyright 2007 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 1020 matching lines @@
 #endif
   }
 }
 
 void SocketTest::SocketRecvTimestamp(const IPAddress& loopback) {
   std::unique_ptr<Socket> socket(
       ss_->CreateSocket(loopback.family(), SOCK_DGRAM));
   EXPECT_EQ(0, socket->Bind(SocketAddress(loopback, 0)));
   SocketAddress address = socket->GetLocalAddress();
 
-  uint64_t send_time_1 = TimeMicros();
+  int64_t send_time_1 = TimeMicros();
   socket->SendTo("foo", 3, address);
   int64_t recv_timestamp_1;
   char buffer[3];
   socket->RecvFrom(buffer, 3, nullptr, &recv_timestamp_1);
   EXPECT_GT(recv_timestamp_1, -1);
 
   const int64_t kTimeBetweenPacketsMs = 100;
   Thread::SleepMs(kTimeBetweenPacketsMs);
 
-  uint64_t send_time_2 = TimeMicros();
+  int64_t send_time_2 = TimeMicros();
   socket->SendTo("bar", 3, address);
   int64_t recv_timestamp_2;
   socket->RecvFrom(buffer, 3, nullptr, &recv_timestamp_2);
 
   int64_t system_time_diff = send_time_2 - send_time_1;
   int64_t recv_timestamp_diff = recv_timestamp_2 - recv_timestamp_1;
   // Compare against the system time at the point of sending, because
   // SleepMs may not sleep for exactly the requested time.
   EXPECT_NEAR(system_time_diff, recv_timestamp_diff, 10000);
 }
 
 }  // namespace rtc