Don't allow changing ICE pool size after SetLocalDescription.

webrtc/api/peerconnectioninterface_unittest.cc

 /*
  *  Copyright 2012 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 2148 matching lines @@
   config.type = PeerConnectionInterface::kRelay;
   EXPECT_TRUE(pc_->SetConfiguration(config));
 
   const cricket::FakePortAllocatorSession* session =
       static_cast<const cricket::FakePortAllocatorSession*>(
           port_allocator_->GetPooledSession());
   ASSERT_NE(nullptr, session);
   EXPECT_EQ(1UL, session->stun_servers().size());
 }
 
+// Test that after SetLocalDescription, changing the pool size is not allowed.
+TEST_F(PeerConnectionInterfaceTest,
+       CantChangePoolSizeAfterSetLocalDescription) {
+  CreatePeerConnection();
+  // Start by setting a size of 1.
+  PeerConnectionInterface::RTCConfiguration config;
+  config.ice_candidate_pool_size = 1;
+  EXPECT_TRUE(pc_->SetConfiguration(config));
+
+  // Set remote offer; can still change pool size at this point.
+  CreateOfferAsRemoteDescription();
+  config.ice_candidate_pool_size = 2;
+  EXPECT_TRUE(pc_->SetConfiguration(config));
+
+  // Set local answer; now it's too late.
+  CreateAnswerAsLocalDescription();
+  config.ice_candidate_pool_size = 3;
+  EXPECT_FALSE(pc_->SetConfiguration(config));
+}
+
 // Test that PeerConnection::Close changes the states to closed and all remote
 // tracks change state to ended.
 TEST_F(PeerConnectionInterfaceTest, CloseAndTestStreamsAndStates) {
   // Initialize a PeerConnection and negotiate local and remote session
   // description.
   InitiateCall();
   ASSERT_EQ(1u, pc_->local_streams()->count());
   ASSERT_EQ(1u, pc_->remote_streams()->count());
 
   pc_->Close();
@@ skipping 803 matching lines @@
   FakeConstraints updated_answer_c;
   answer_c.SetMandatoryReceiveAudio(false);
   answer_c.SetMandatoryReceiveVideo(false);
 
   cricket::MediaSessionOptions updated_answer_options;
   EXPECT_TRUE(
       ParseConstraintsForAnswer(&updated_answer_c, &updated_answer_options));
   EXPECT_TRUE(updated_answer_options.has_audio());
   EXPECT_TRUE(updated_answer_options.has_video());
 }