Strip comments and whitespace from javascript resources

tools/grit/grit_rule.gni

Index: tools/grit/grit_rule.gni
diff --git a/tools/grit/grit_rule.gni b/tools/grit/grit_rule.gni
index b77a24d5e6fb3f2f429bb47c8f71fcea2941774e..4940775f53bde891d5d9a86ed85b3d642574d008 100644
--- a/tools/grit/grit_rule.gni
+++ b/tools/grit/grit_rule.gni
@@ -303,6 +303,8 @@ if (mac_views_browser) {
 grit_resource_id_file = "//tools/gritsettings/resource_ids"
 grit_info_script = "//tools/grit/grit_info.py"
 
+js_minifier = rebase_path("//third_party/closure_compiler/js_minify.py")
+
 template("grit") {
   assert(defined(invoker.source),
          "\"source\" must be defined for the grit template $target_name")
@@ -441,6 +443,13 @@ template("grit") {
 
     args += grit_flags + assert_files_flags
 
+    if (strip_resource_files) {
+      args += [
+        "--js-minifier",
+        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