Enable UBSan float-cast-overflow warnings and fix existing ones

webrtc/BUILD.gn

 # Copyright (c) 2014 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.
 
 # TODO(kjellander): Rebase this to webrtc/build/common.gypi changes after r6330.
 
@@ skipping 75 matching lines @@
   if (is_chromeos) {
     defines += [ "CHROMEOS" ]
   }
 
   if (rtc_sanitize_coverage != "") {
     assert(is_clang, "sanitizer coverage requires clang")
     cflags += [ "-fsanitize-coverage=${rtc_sanitize_coverage}" ]
     ldflags += [ "-fsanitize-coverage=${rtc_sanitize_coverage}" ]
   }
 
+  if (is_ubsan) {
+    cflags += [ "-fsanitize=float-cast-overflow" ]
+  }
+
   # TODO(GYP): Support these in GN.
   # if (is_bsd) {
   #   defines += [ "BSD" ]
   # }
   # if (is_openbsd) {
   #   defines += [ "OPENBSD" ]
   # }
   # if (is_freebsd) {
   #   defines += [ "FREEBSD" ]
   # }
@@ skipping 425 matching lines @@
       ]
 
       deps = [
         "examples:AppRTCMobile_javalib",
         "sdk/android:libjingle_peerconnection_java",
         "//base:base_java_test_support",
       ]
     }
   }
 }