Prepare for -Wall for third-party code, -Wextra for chromium_code

base/allocator/BUILD.gn

 # Copyright (c) 2013 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.
 
 import("//build/config/allocator.gni")
 import("//build/config/compiler/compiler.gni")
 
 declare_args() {
   # Provide a way to force disable debugallocation in Debug builds,
   # e.g. for profiling (it's more rare to profile Debug builds,
@@ skipping 30 matching lines @@
 }
 
 config("tcmalloc_flags") {
   if (enable_debugallocation) {
     defines = [
       # Use debugallocation for Debug builds to catch problems early
       # and cleanly, http://crbug.com/30715 .
       "TCMALLOC_FOR_DEBUGALLOCATION",
     ]
   }
+  if (is_clang) {
+    cflags = [
+      # tcmalloc initializes some fields in the wrong order.
+      "-Wno-reorder",
+
+      # tcmalloc contains some unused local template specializations.
+      "-Wno-unused-function",
+
+      # tcmalloc uses COMPILE_ASSERT without static_assert but with
+      # typedefs.
+      "-Wno-unused-local-typedefs",
+
+      # for magic2_ in debugallocation.cc (only built in Debug builds)
+      # typedefs.
+      "-Wno-unused-private-field",
+    ]
+  }
 }
 
 # This config and libc modification are only used on Windows.
 if (is_win) {
   import("//build/config/win/visual_studio_version.gni")
 
   config("nocmt") {
     ldflags = [
       "/NODEFAULTLIB:libcmt",
       "/NODEFAULTLIB:libcmtd",
@@ skipping 206 matching lines @@
     # Make sure the allocation library is optimized as much as possible when
     # we"re in release mode.
     if (!is_debug) {
       configs -= [ "//build/config/compiler:default_optimization" ]
       configs += [ "//build/config/compiler:optimize_max" ]
     }
 
     deps += [ "//base/third_party/dynamic_annotations" ]
   }
 }  # !is_android