Disable RTC in coverage builds.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1865 matching lines @@
             'cflags': [ '-ftest-coverage',
                         '-fprofile-arcs' ],
             'link_settings': { 'libraries': [ '-lgcov' ] },
           }],
           ['OS=="win"', {
             'variables': {
               # Disable incremental linking for all modules.
               # 0: inherit, 1: disabled, 2: enabled.
               'msvs_debug_link_incremental': '1',
               'msvs_large_module_debug_link_mode': '1',
+              # Disable RTC. Syzygy explicitly doesn't support RTC instrumented
+              # binaries for now.
+              'win_debug_RuntimeChecks': '0',

[chrisha, 2013/02/12 18:37:05]

It's not immediately evident looking at the diff, but we're in the 'coverage!=0'
block here.

             },
             'defines': [
               # Disable iterator debugging (huge speed boost without any
               # change in coverage results).
               '_HAS_ITERATOR_DEBUGGING=0',
             ],
             'msvs_settings': {
               'VCLinkerTool': {
                 # Enable profile information (necessary for coverage
                 # instrumentation). This is incompatible with incremental
@@ skipping 2133 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }