Treat linker warnings as errors on all POSIX platforms

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 2954 matching lines @@
             'inherit_from': ['Common_Base', 'x64_Base', 'Release_Base'],
           },
         }],
       ],
     },
   },
   'conditions': [
     ['os_posix==1', {
       'target_defaults': {
         'ldflags': [
+          '-Wl,--fatal-warnings',

[Nico, 2014/03/16 16:56:14]

Should this only be done if werror% isn't empty?

           '-Wl,-z,now',
           '-Wl,-z,relro',
         ],
       },
     }],
     ['os_posix==1 and chromeos==0', {
       # Chrome OS enables -fstack-protector-strong via its build wrapper,
       # and we want to avoid overriding this, so stack-protector is only
       # enabled when not building on Chrome OS.
       # TODO(phajdan.jr): Use -fstack-protector-strong when our gcc
@@ skipping 57 matching lines @@
             'defines': [
               '_DEBUG',
             ],
             'cflags': [
               '-O>(debug_optimize)',
               '-g',
             ],
             'conditions' : [
               ['OS=="android"', {
                 'ldflags': [
-                  '-Wl,--fatal-warnings',
                   # Only link with needed input sections. This is to avoid
                   # getting undefined reference to __cxa_bad_typeid in the CDU
                   # library.
                   '-Wl,--gc-sections',
                   # Warn in case of text relocations.
                   '-Wl,--warn-shared-textrel',
                 ],
               }],
               ['OS=="android" and android_full_debug==0', {
                 # Some configurations are copied from Release_Base to reduce
@@ skipping 61 matching lines @@
                 ],
               }],
               ['OS=="android"', {
                 'variables': {
                   'release_optimize%': 's',
                 },
                 'cflags': [
                   '-fomit-frame-pointer',
                 ],
                 'ldflags': [
-                  '-Wl,--fatal-warnings',
                   # Warn in case of text relocations.
                   '-Wl,--warn-shared-textrel',
                 ],
               }],
               ['clang==1', {
                 'cflags!': [
                   '-fno-ident',
                 ],
               }],
               ['profiling==1', {
@@ skipping 1897 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',
   },
 }