Adds -Wno-deprecated-register to the build settings for iOS.

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 4421 matching lines @@
           'CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS': 'YES',
           'WARNING_CFLAGS': [
             '-Wheader-hygiene',
             # Don't die on dtoa code that uses a char as an array index.
             # This is required solely for base/third_party/dmg_fp/dtoa.cc.
             '-Wno-char-subscripts',
             # See comment in the mac clang section above for this flag.
             '-Wno-unneeded-internal-declaration',
             # Match OS X clang C++11 warning settings.
             '-Wno-c++11-narrowing',
+            # As of Xcode 5.1, the register keyword is deprecated, but Chromium
+            # code still uses it.
+            '-Wno-deprecated-register',
           ],
 
-          # Limit the valid architectures depending on "target_subarch".
-          # This need to include the "arm" architectures but also the "x86"
-          # ones (they are used when building for the simulator).
           'conditions': [
+            # Older Xcodes do not support -Wno-deprecated-register, so pass an
+            # additional flag to suppress the "unknown compiler option" error.
+            # Restrict this flag to builds that are either compiling with Xcode
+            # or compiling with Xcode's Clang.  This will allow Ninja builds to
+            # continue failing on unknown compiler options.
+            # TODO(rohitrao): This flag is temporary and should be removed as
+            # soon as the iOS bots are updated to use Xcode 5.1.
+            ['"<(GENERATOR)"=="xcode" or clang_xcode==1', {
+              'WARNING_CFLAGS': [
+                '-Wno-unknown-warning-option',
+              ],
+            }],
+
+            # Limit the valid architectures depending on "target_subarch".
+            # This need to include the "arm" architectures but also the "x86"
+            # ones (they are used when building for the simulator).
             ['target_subarch=="arm32"', {
               'VALID_ARCHS': ['armv7', 'i386'],
             }],
             ['target_subarch=="arm64"', {
               'VALID_ARCHS': ['arm64', 'x86_64'],
             }],
             ['target_subarch=="both"', {
               'VALID_ARCHS': ['arm64', 'armv7', 'x86_64', 'i386'],
             }],
           ],
@@ skipping 570 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',
   },
 }