linux/clang: Disable the last two warnings, turn on -Werror

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 1600 matching lines @@
         ],
       }],
       ['chromium_code==0', {
         'conditions': [
           [ 'os_posix==1 and OS!="mac" and OS!="ios"', {
             # We don't want to get warnings from third-party code,
             # so remove any existing warning-enabling flags like -Wall.
             'cflags!': [
               '-Wall',
               '-Wextra',
-              '-Werror',
             ],
             'cflags_cc': [
               # Don't warn about hash_map in third-party code.
               '-Wno-deprecated',
             ],
             'cflags': [
               # Don't warn about printf format problems.
               # This is off by default in gcc but on in Ubuntu's gcc(!).
               '-Wno-format',
             ],
             'cflags_cc!': [
               # TODO(fischman): remove this.
               # http://code.google.com/p/chromium/issues/detail?id=90453
               '-Wsign-compare',
             ]
           }],
+          # TODO: Fix all warnings on chromeos too.
+          [ 'os_posix==1 and OS!="mac" and OS!="ios" and (clang!=1 or chromeos==1)', {
+            'cflags!': [
+              '-Werror',
+            ],
+          }],
           [ 'os_posix==1 and os_bsd!=1 and OS!="mac" and OS!="android"', {
             'cflags': [
               # Don't warn about ignoring the return value from e.g. close().
               # This is off by default in some gccs but on by default in others.
               # BSD systems do not support this option, since they are usually
               # using gcc 4.2.1, which does not have this flag yet.
               '-Wno-unused-result',
             ],
           }],
           [ 'OS=="win"', {
@@ skipping 1735 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',
   },
 }