Allocator shim skeleton + Linux impl behind a build flag

base/allocator/allocator_shim_override_cpp_symbols.h

Index: base/allocator/allocator_shim_override_cpp_symbols.h
diff --git a/base/allocator/allocator_shim_override_cpp_symbols.h b/base/allocator/allocator_shim_override_cpp_symbols.h
new file mode 100644
index 0000000000000000000000000000000000000000..616716fb96f0dda2bc94d18ab18616c5e9acc3f3
--- /dev/null
+++ b/base/allocator/allocator_shim_override_cpp_symbols.h
@@ -0,0 +1,42 @@
+// 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"
+
+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);