Fix official build in GN

chrome/version.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.
 
 # Runs the version processing script over the given template file to produce
 # an output file. This is used for generating various forms of files that
 # incorporate the product name and version.
 #
-# This template automatically includes VERSION, LASTCHANGE, and BRANDING,
+# This template automatically includes VERSION, LASTCHANGE, and BRANDING. It
+# automatically uses the template file .
+# GYP parameterizes this template file but all current invocations use this
+# same one. If in the future we need to set it, this should be added as an
+# optional argument.
+#
+# In GYP this is a rule that runs once per ".ver" file. In GN this just
+# processes one file per invocation of the template so you may have to have
+# multiple targets.
 #
 # Parameters:
-#   source:
-#     File name of source template file to read.
+#   sources (optional):
+#     List of file names to read. In GYP, this should list the 'source' (see
+#     above) as well as any extra_variable_files.
 #
 #   output:
-#     File name of file to write.
+#     File name of file to write. In GYP this is unspecified and it will
+#     make up a file name for you based on the input name, and tack on
+#     "_version.rc" to the end. But in GN you need to specify the full name.
+#
+#   template_file (optional):
+#     Template file to use (not a list). Defaults to
+#     //chrome/app/chrome_version.rc.version if unspecified.
 #
 #   extra_args (optional):
-#     Extra arguments to pass to version.py.
+#     Extra arguments to pass to version.py. Any "-f <filename>" args should
+#     use sources instead.
 #
 #   visibility (optional)
 #
 # Example:
 #   process_version("myversion") {
-#     source = "myfile.h.in"
+#     sources = [ ""myfile.h.in"

[Dirk Pranke, 2015/02/25 00:23:19]

Nit: you have two leading quotes and a missing end brace.

 #     output = "$target_gen_dir/myfile.h"
 #     extra_args = ["-e", "FOO=42"]
+#     extra_files = [ "foo/BRANDING" ]
 #   }
 template("process_version") {
-  assert(defined(invoker.source), "Source must be defined for $target_name")
+  assert(defined(invoker.sources) || defined(invoker.template_file),
+         "sources or template_file must be defined for $target_name")

[Dirk Pranke, 2015/02/25 00:23:19]

It's not actually clear in the docs above that you must specify either sources
or template_file. Is that correct? If so, you should fix the docs, and I'd also
change this to "Either sources or template_file ..." to be a bit more
grammatical.

   assert(defined(invoker.output), "Output must be defined for $target_name")
 
   action(target_name) {
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     script = "//build/util/version.py"
 
     lastchange_path = "//build/util/LASTCHANGE"
     version_path = "//chrome/VERSION"
     if (is_chrome_branded) {
       branding_path = "//chrome/app/theme/google_chrome/BRANDING"
     } else {
       branding_path = "//chrome/app/theme/chromium/BRANDING"
     }
+    if (defined(invoker.template_file)) {
+      template_path = invoker.template_file
+    } else {
+      template_path = "//chrome/app/chrome_version.rc.version"
+    }
 
     inputs = [
       version_path,
-      invoker.source,
       lastchange_path,
       branding_path,
+      template_path

[Dirk Pranke, 2015/02/25 00:23:19]

nit: should there be a trailing comma?

     ]
 
     outputs = [
       invoker.output,
     ]
 
-    args = [
+    args = []
+
+    if (defined(invoker.sources)) {
+      inputs += invoker.sources
+      foreach(i, invoker.sources) {
+        args += [ "-f", rebase_path(i, root_build_dir) ]
+      }
+    }
+
+    args += [
       "-f",
       rebase_path(version_path, root_build_dir),
       "-f",
       rebase_path(branding_path, root_build_dir),
       "-f",
       rebase_path(lastchange_path, root_build_dir),
-      "-i",
-      rebase_path(invoker.source, root_build_dir),
-      "-o",
+      rebase_path(template_path, root_build_dir),
       rebase_path(invoker.output, root_build_dir),
     ]
 
     if (defined(invoker.extra_args)) {
       args += invoker.extra_args
     }
   }
 }