Fixing integer overflow when parsing bandwidth attribute.

It's still valid SDP so just clamp it at INT_MAX.

BUG=chromium:648071

Review-Url: https://codereview.webrtc.org/2571073002
Cr-Commit-Position: refs/heads/master@{#15582}
diff --git a/webrtc/api/webrtcsdp.cc b/webrtc/api/webrtcsdp.cc
index f0e94b6..f18653d 100644
--- a/webrtc/api/webrtcsdp.cc
+++ b/webrtc/api/webrtcsdp.cc
@@ -2641,6 +2641,8 @@
                         << cricket::kDataMaxBandwidth / 1000 << "kbps.";
             return ParseFailed(line, description.str(), error);
           }
+          // Prevent integer overflow.
+          b = std::min(b, INT_MAX / 1000);
           media_desc->set_bandwidth(b * 1000);
         }
       }