Dump all .xcconfigs. They're no longer used, all of these settings are in GY...

build/common.xcconfig

Index: build/common.xcconfig
===================================================================
--- build/common.xcconfig	(revision 21955)
+++ build/common.xcconfig	(working copy)
@@ -1,31 +0,0 @@
-// Copyright (c) 2008 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.
-
-ALWAYS_SEARCH_USER_PATHS = NO
-GCC_C_LANGUAGE_STANDARD = c99
-GCC_CW_ASM_SYNTAX = NO
-GCC_DYNAMIC_NO_PIC = YES
-GCC_ENABLE_PASCAL_STRINGS = NO
-GCC_INLINES_ARE_PRIVATE_EXTERN = YES
-GCC_PRECOMPILE_PREFIX_HEADER = YES
-GCC_SYMBOLS_PRIVATE_EXTERN = YES
-GCC_TREAT_WARNINGS_AS_ERRORS = YES
-GCC_VERSION = 4.2
-GCC_WARN_ABOUT_MISSING_NEWLINE = YES
-OTHER_LDFLAGS = $(OTHER_LDFLAGS) $(CODECOVERAGE_OTHER_LDFLAGS)
-PREBINDING = NO
-
-// We're only supporting 10.5 and later
-SDKROOT = $(DEVELOPER_SDK_DIR)/MacOSX10.5.sdk
-MACOSX_DEPLOYMENT_TARGET = 10.5
-
-// Each project file must set XCODEPROJ_DEPTH as a project-wide setting.  It
-// should contain a relative path to reach the src directory from the
-// directory containing the project.  For example, src/base/base.xcodeproj
-// should set XCODEPROJ_DEPTH = ../.. .  This is used to redirect all build
-// output to a single common directory.
-SYMROOT = $(XCODEPROJ_DEPTH)/xcodebuild
-
-USE_HEADERMAP = NO
-WARNING_CFLAGS = $(WARNING_CFLAGS) -Wall -Wendif-labels