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

build/debug.xcconfig

Index: build/debug.xcconfig
===================================================================
--- build/debug.xcconfig	(revision 21955)
+++ build/debug.xcconfig	(working copy)
@@ -1,27 +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.
-
-#include "common.xcconfig"
-
-COPY_PHASE_STRIP = NO
-GCC_OPTIMIZATION_LEVEL = 0
-// Would be nice to define DEBUG to prevent against people incorrectly using
-// it intstead of !NDEBUG, but it causes libxml to spew diagnostic info all
-// over our layout tests.
-// GCC_PREPROCESSOR_DEFINITIONS = $(GCC_PREPROCESSOR_DEFINITIONS) DEBUG
-// Additional libc++ strictness; disabled because they break some things in
-// WebKit and some additional things when building with gcc 4.2.
-// GCC_PREPROCESSOR_DEFINITIONS = $(GCC_PREPROCESSOR_DEFINITIONS) DEBUG _GLIBCXX_CONCEPT_CHECKS _GLIBCXX_DEBUG _GLIBCXX_DEBUG_PEDANTIC
-OTHER_CFLAGS = $(OTHER_CFLAGS) -fstack-protector -fstack-protector-all
-
-// Code coverage support via gcov is disabled for normal debug builds because
-// our build structure results in many "merge mismatch for summaries" messages
-// being printed at the conclusion of many tests in many depend build cases, as
-// well as a long delay while summary data is written.  Since these are not
-// needed in the majority of debug builds, code coverage is left off, but it
-// can be easily enabled by uncommenting the next section.
-//
-//GCC_GENERATE_TEST_COVERAGE_FILES = YES
-//GCC_INSTRUMENT_PROGRAM_FLOW_ARCS = YES
-//CODECOVERAGE_OTHER_LDFLAGS = -lgcov