[Android] Add gyp support for multidex.

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 922 matching lines @@
 # Declare a java library target for a prebuilt jar
 #
 # Variables
 #   deps: Specifies the dependencies of this target. Java targets in this list
 #     will be added to the javac classpath.
 #   jar_path: Path to the prebuilt jar.
 #   jar_dep: Target that builds jar_path (optional).
 #   proguard_preprocess: If true, proguard preprocessing will be run. This can
 #     be used to remove unwanted parts of the library.
 #   proguard_config: Path to the proguard config for preprocessing.
+#   supports_android: If true, Android targets (android_library, android_apk)
+#     may depend on this target. Note: if true, this target must only use the
+#     subset of Java available on Android.
 #
 # Example
 #   java_prebuilt("foo_java") {
 #     jar_path = "foo.jar"
 #     deps = [
 #       ":foo_resources",
 #       ":bar_java"
 #     ]
 #   }
 template("java_prebuilt") {
@@ skipping 1021 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) {
   }
 }