Workaround for issue breaking NACL on ChromeOS.

base/allocator/debugallocation_shim.cc

Index: base/allocator/debugallocation_shim.cc
diff --git a/base/allocator/debugallocation_shim.cc b/base/allocator/debugallocation_shim.cc
index d1cf52a23ea9f181fa92d3880837b8e2fd1c784f..1ca3049cacd4b9065bd73a84f33d53564bd5e0a2 100644
--- a/base/allocator/debugallocation_shim.cc
+++ b/base/allocator/debugallocation_shim.cc
@@ -2,6 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Workaround for crosbug:629593.  Using AFDO on the tcmalloc files is
+// causing problems. The tcmalloc files depend on stack layouts and
+// AFDO can mess with them. Better not to use AFDO there.  This is a
+// temporary hack. We will add a mechanism in the build system to
+// avoid using -fauto-profile for tcmalloc files.
+#if !defined(__clang__)
+#pragma GCC optimize ("no-auto-profile")
+#endif
+
 #if defined(TCMALLOC_FOR_DEBUGALLOCATION)
 #include "third_party/tcmalloc/chromium/src/debugallocation.cc"
 #else