Add support for overriding keystore for signing.

build/config/android/rules.gni

 # Copyright 2014 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("//base/android/linker/config.gni")
 import("//build/config/android/config.gni")
 import("//build/config/android/internal_rules.gni")
 import("//build/toolchain/toolchain.gni")
 import("//third_party/android_platform/config.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 1161 matching lines @@
 
   _version_code = "1"
   if (defined(invoker.version_code)) {
     _version_code = invoker.version_code
   }
 
   _version_name = "Developer Build"
   if (defined(invoker.version_name)) {
     _version_name = invoker.version_name
   }
-  _keystore_path = android_default_keystore_path
-  _keystore_name = android_default_keystore_name
-  _keystore_password = android_default_keystore_password
+  _keystore_path = android_keystore_path
+  _keystore_name = android_keystore_name
+  _keystore_password = android_keystore_password
 
   if (defined(invoker.keystore_path)) {
     _keystore_path = invoker.keystore_path
     _keystore_name = invoker.keystore_name
     _keystore_password = invoker.keystore_password
   }
 
   _srcjar_deps = []
   if (defined(invoker.srcjar_deps)) {
     _srcjar_deps += invoker.srcjar_deps
@@ skipping 810 matching lines @@
 
 # TODO(GYP): implement this.
 template("uiautomator_test") {
   set_sources_assignment_filter([])
   forward_variables_from(invoker, [ "testonly" ])
   assert(target_name != "")
   assert(invoker.deps != [] || true)
   group(target_name) {
   }
 }