Compile specific parts of the Android build with -O2.

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")
 
 # Only executables and not libraries should depend on the allocator target;
 # only the application (the final executable) knows what allocator makes sense.
 # This "allocator" meta-target will forward to the default allocator according
 # to the build settings.
@@ skipping 227 matching lines @@
     }
   }
 }  # !is_android
 
 source_set("allocator_extension_thunks") {
   visibility = [ "//base/*" ]
   sources = [
     "allocator_extension_thunks.cc",
     "allocator_extension_thunks.h",
   ]
+  if (is_android && !is_debug) {
+    configs -= [ "//build/config/compiler:optimize" ]
+    configs += [ "//build/config/compiler:optimize_max" ]
+  }
 }