Fix integer overflow in ProbeController.

webrtc/modules/congestion_controller/probe_controller_unittest.cc

 /*
  *  Copyright (c) 2016 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.
  */
 #include <memory>
@@ skipping 65 matching lines @@
 
   EXPECT_CALL(pacer_, CreateProbeCluster(kMaxBitrateBps + 100, _));
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps + 100);
 }
 
 TEST_F(ProbeControllerTest, TestExponentialProbing) {
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps);
 
-  // Repeated probe should only be sent when estimated bitrate climbs above 4 *
-  // kStartBitrateBps = 1200.
+  // Repeated probe should only be sent when estimated bitrate climbs above
+  // 0.7 * 6 * kStartBitrateBps = 1260.
   EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(0);
   probe_controller_->SetEstimatedBitrate(1000);
   testing::Mock::VerifyAndClearExpectations(&pacer_);
 
   EXPECT_CALL(pacer_, CreateProbeCluster(2 * 1800, _));
   probe_controller_->SetEstimatedBitrate(1800);
 }
 
 TEST_F(ProbeControllerTest, TestExponentialProbingTimeout) {
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
@@ skipping 55 matching lines @@
 
   EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(1);
   EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
       .WillRepeatedly(Return(rtc::Optional<int64_t>(start_time)));
   clock_.AdvanceTimeMilliseconds(1000);
   probe_controller_->Process();
   probe_controller_->SetEstimatedBitrate(500);
   testing::Mock::VerifyAndClearExpectations(&pacer_);
 }
 
+TEST_F(ProbeControllerTest, TestExponentialProbingOverflow) {
+  const int64_t kMbpsMultiplier = 1000000;
+  probe_controller_->SetBitrates(kMinBitrateBps, 10 * kMbpsMultiplier,
+                                 100 * kMbpsMultiplier);
+
+  // Verify that probe bitrate is capped at the specified max bitrate
+  EXPECT_CALL(pacer_, CreateProbeCluster(100 * kMbpsMultiplier, _));
+  probe_controller_->SetEstimatedBitrate(60 * kMbpsMultiplier);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+
+  // Verify that repeated probes aren't sent.
+  EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(0);
+  probe_controller_->SetEstimatedBitrate(100 * kMbpsMultiplier);
+}
+
 }  // namespace test
 }  // namespace webrtc