android: Use use_goma=1 gomadir gyp defines instead of magic GOMA_DIR env var.

build/toolchain/goma.gni

 # 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.
 
 # Defines the configuration of Goma.
 #
 # This is currently designed to match the GYP build exactly, so as not to break
 # people during the transition.
-#
-# TODO(brettw) make Android work like normal Linux. It's silly that Android has
-# completely different logic for configuring Goma.
 
 declare_args() {
   use_goma = false
 
   goma_dir = ""
 }
 
-# The Android GYP build has some logic that automatically turns on goma when
-# the directory is set, but this isn't done for other platforms.
-# TODO(brettw) rationalize all Linux-y platforms.
-if (is_android) {
-  if (goma_dir == "") {
-    goma_dir = exec_script("android/default_goma_for_android.py", [], "value")
-  }
-  if (goma_dir != "") {
-    use_goma = true
-  }
-}
-
 if (use_goma && goma_dir == "") {
   # Set the default goma directory. This must be a character-for-character
   # match for the GYP default or else the compilers for the different targets
   # won't match and GYP will assert.
   if (is_win) {
     goma_dir = "c:\goma\goma-win"
   } else {
     goma_dir = exec_script("get_default_posix_goma_dir.py", [], "value")
   }
 }
 
 if (use_goma) {
   # Define the toolchain for the GYP build when using goma.
   make_goma_global_settings =
     "['CC_wrapper', '$goma_dir/gomacc']," +
     "['CXX_wrapper', '$goma_dir/gomacc']," +
     "['CC.host_wrapper', '$goma_dir/gomacc']," +
     "['CXX.host_wrapper', '$goma_dir/gomacc'],"
 }