Hook up allocator shim on mac.

base/allocator/allocator_shim_override_cpp_symbols.h

 // Copyright 2016 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.
 
 #ifdef BASE_ALLOCATOR_ALLOCATOR_SHIM_OVERRIDE_CPP_SYMBOLS_H_
 #error This header is meant to be included only once by allocator_shim.cc
 #endif
 #define BASE_ALLOCATOR_ALLOCATOR_SHIM_OVERRIDE_CPP_SYMBOLS_H_
 
 // Alias the default new/delete C++ symbols to the shim entry points.
 // This file is strongly inspired by tcmalloc's libc_override_redefine.h.
 
 #include <new>
 
 #include "base/allocator/allocator_shim_internals.h"
 
+#if defined(OS_MACOSX)

[Primiano Tucci (use gerrit), 2017/01/28 05:10:02]

just checking: do we actually need these?
IIRC the reason why I had to introduce them was because the stdlibc++ on linux
was directly going to __libc_malloc, so was bypassing the malloc-shim.
For instance, on Windows we don't need to override the C++ symbols because they
under the hood end up through malloc.
I have no idea about the current situation on Mac OS. My only question is: what
do we do today for the suicide-on-OOM feature? IIRC on Mac today we don't
override the c++ symbols.
Essentially what I am saying here is:
- either the current suicide-on-oom logic is bugged, and we don't suicide on
"new" failure
OR
- this is unnecessary and you can just piggy back on the #if !defined(OS_WIN) of
allocator_shim.cc:246

[erikchen, 2017/01/31 02:21:22]

We don't, the implementation of libc++.dylib forwards to default malloc zone.

+
+SHIM_ALWAYS_EXPORT void* operator new(size_t size) {
+  return ShimCppNew(size);
+}
+
+SHIM_ALWAYS_EXPORT void operator delete(void* ptr)__THROW {
+  return ShimCppDelete(ptr);
+}
+
+SHIM_ALWAYS_EXPORT void* operator new[](size_t size) {
+  return ShimCppNew(size);
+}
+
+SHIM_ALWAYS_EXPORT void operator delete[](void* ptr) __THROW {
+  return ShimCppDelete(ptr);
+}
+
+SHIM_ALWAYS_EXPORT void* operator new(size_t size,
+                                      const std::nothrow_t&) __THROW {
+  return ShimCppNew(size);
+}
+
+SHIM_ALWAYS_EXPORT void* operator new[](size_t size,
+                                        const std::nothrow_t&) __THROW {
+  return ShimCppNew(size);
+}
+
+SHIM_ALWAYS_EXPORT void operator delete(void* ptr,
+                                        const std::nothrow_t&)__THROW {
+  ShimCppDelete(ptr);
+}
+
+SHIM_ALWAYS_EXPORT void operator delete[](void* ptr,
+                                          const std::nothrow_t&) __THROW {
+  ShimCppDelete(ptr);
+}
+
+#else  // !OS_MACOSX
+
 SHIM_ALWAYS_EXPORT void* operator new(size_t size)
     SHIM_ALIAS_SYMBOL(ShimCppNew);
 
 SHIM_ALWAYS_EXPORT void operator delete(void* p) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppDelete);
 
 SHIM_ALWAYS_EXPORT void* operator new[](size_t size)
     SHIM_ALIAS_SYMBOL(ShimCppNew);
 
 SHIM_ALWAYS_EXPORT void operator delete[](void* p) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppDelete);
 
 SHIM_ALWAYS_EXPORT void* operator new(size_t size,
                                       const std::nothrow_t&) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppNew);
 
 SHIM_ALWAYS_EXPORT void* operator new[](size_t size,
                                         const std::nothrow_t&) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppNew);
 
 SHIM_ALWAYS_EXPORT void operator delete(void* p, const std::nothrow_t&) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppDelete);
 
 SHIM_ALWAYS_EXPORT void operator delete[](void* p,
                                           const std::nothrow_t&) __THROW
     SHIM_ALIAS_SYMBOL(ShimCppDelete);
+
+#endif  // OS_MACOSX