Enable -Wformat in linux, android, chromeos, cast 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 3128 matching lines @@
           ],
         },
         'conditions': [
           [ 'os_posix==1 and OS!="mac" and OS!="ios"', {
             # Remove -Wextra for third-party code.
             'cflags!': [ '-Wextra' ],
             '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',
-            ],
           }],
           [ 'os_posix==1 and clang!=1 and OS!="mac" and OS!="ios"', {
             # When we don't control the compiler, don't use -Wall for
             # third-party code either.
             'cflags!': [ '-Wall' ],
           }],
           # TODO: Fix all warnings on chromeos too.
           [ 'os_posix==1 and OS!="mac" and OS!="ios" and (clang!=1 or chromeos==1)', {
             'cflags!': [
               '-Werror',
@@ skipping 3259 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',
   },
 }