Reland #1: Switch the default build configuration to use the 10.10 SDK.

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 1883 matching lines @@
           # Normally, mac_sdk_min is used to find an SDK that Xcode knows
           # about that is at least the specified version. In official builds,
           # the SDK must match mac_sdk_min exactly. If the SDK is installed
           # someplace that Xcode doesn't know about, set mac_sdk_path to the
           # path to the SDK; when set to a non-empty string, SDK detection
           # based on mac_sdk_min will be bypassed entirely.
           'conditions': [
             ['OS=="ios"', {
               'mac_sdk_min%': '10.8',
             }, {  # else OS!="ios"
-              'mac_sdk_min%': '10.6',
+              'mac_sdk_min%': '10.10',
             }],
           ],
           'mac_sdk_path%': '',
 
           'mac_deployment_target%': '10.6',
         },
 
         'mac_sdk_min': '<(mac_sdk_min)',
         'mac_sdk_path': '<(mac_sdk_path)',
         'mac_deployment_target': '<(mac_deployment_target)',
@@ skipping 4368 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',
   },
 }