Strip comments and whitespace from javascript resources

tools/grit/grit_rule.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.
 
 # Instantiate grit. This will produce a script target to run grit, and a
 # static library that compiles the .cc files.
 #
 # Parameters
 #
 #   source (required)
@@ skipping 64 matching lines @@
 #     ]
 #
 #     grit_flags = [ "-E", "foo=bar" ]  # Optional extra flags.
 #     # You can also put deps here if the grit source depends on generated
 #     # files.
 #   }
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
+import("//third_party/closure_compiler/closure_args.gni")
 
 declare_args() {
   # Enables used resource whitelist generation.
   enable_resource_whitelist_generation = false
 }
 
 grit_defines = []
 
 # Mac and iOS want Title Case strings.
 use_titlecase_in_grd_files = is_mac || is_ios
@@ skipping 198 matching lines @@
     "enable_service_discovery",
   ]
 }
 if (mac_views_browser) {
   grit_defines += [
     "-D",
     "mac_views_browser",
   ]
 }
 
+# TODO(aberent): Enable for other platforms once the build machines have
+#                Java on them (and hence can run the closure compiler).
+_strip_resource_files = is_android
+_js_minifier = "//third_party/closure_compiler/js_minify.py"
+
 grit_resource_id_file = "//tools/gritsettings/resource_ids"
 grit_info_script = "//tools/grit/grit_info.py"
 
 template("grit") {
   assert(defined(invoker.source),
          "\"source\" must be defined for the grit template $target_name")
 
   grit_inputs = [ invoker.source ]
 
   if (defined(invoker.resource_ids)) {
@@ skipping 121 matching lines @@
       foreach(i, invoker.defines) {
         args += [
           "-D",
           i,
         ]
       }
     }
 
     args += grit_flags + assert_files_flags
 
+    if (_strip_resource_files) {
+      js_minifier_command = rebase_path(_js_minifier)
+      js_minifier_command = "$js_minifier_command --closure_args"
+      foreach(closure_arg,
+              common_closure_args + minifying_closure_args +
+                  default_disabled_closure_args) {
+        js_minifier_command = "$js_minifier_command $closure_arg"
+      }
+      args += [
+        "--js-minifier",
+        js_minifier_command,
+      ]
+      inputs += [ _js_minifier ]
+    }
+
     if (defined(invoker.visibility)) {
       # This needs to include both what the invoker specified (since they
       # probably include generated headers from this target), as well as the
       # generated source set (since there's no guarantee that the visibility
       # specified by the invoker includes our target).
       #
       # Only define visibility at all if the invoker specified it. Otherwise,
       # we want to keep the public "no visibility specified" default.
       visibility = target_visibility + invoker.visibility
     }
@@ skipping 32 matching lines @@
     if (defined(invoker.configs)) {
       configs += invoker.configs
     }
 
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     output_name = grit_output_name
   }
 }