chrome_repack_locales: compress .pak files on Chrome OS

This CL adds support for compressing .pak files, and adds compression
for locales/*.pak on chromeos.

Note: We keep the extension for compressed .pak files to avoid
dependency complexity in tests.

Bug: 1017864
Change-Id: Ifee472b7e15673fcb835ae75aca768265592460b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1912621
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715173}

chrome/chrome_repack_locales.gni

@@ -78,6 +78,7 @@ template("chrome_repack_locales") {
         "//remoting/resources",
         "//ui/chromeos/strings",
       ]
+      compress = true
     }
     if (enable_extensions) {
       source_patterns +=

tools/grit/grit/format/data_pack.py

@@ -215,7 +215,8 @@ def ReadGrdInfo(grd_file):
 
 
 def RePack(output_file, input_files, whitelist_file=None,
-           suppress_removed_key_output=False):
+           suppress_removed_key_output=False,
+           output_info_filepath=None):
   """Write a new data pack file by combining input pack files.
 
   Args:
@@ -226,6 +227,7 @@ def RePack(output_file, input_files, whitelist_file=None,
                       all resources.
       suppress_removed_key_output: allows the caller to suppress the output from
                                    RePackFromDataPackStrings.
+      output_info_file: If not None, specify the output .info filepath.
 
   Raises:
       KeyError: if there are duplicate keys or resource encoding is
@@ -243,7 +245,9 @@ def RePack(output_file, input_files, whitelist_file=None,
   resources, encoding = RePackFromDataPackStrings(
       inputs, whitelist, suppress_removed_key_output)
   WriteDataPack(resources, output_file, encoding)
-  with open(output_file + '.info', 'w') as output_info_file:
+  if output_info_filepath is None:
+    output_info_filepath = output_file + '.info'
+  with open(output_info_filepath, 'w') as output_info_file:
     for filename in input_info_files:
       with open(filename, 'r') as info_file:
         output_info_file.writelines(info_file.readlines())

tools/grit/pak_util.py

@@ -12,9 +12,12 @@ https://dev.chromium.org/developers/design-documents/linuxresourcesandlocalizeds
 from __future__ import print_function
 
 import argparse
+import gzip
 import hashlib
 import os
+import shutil
 import sys
+import tempfile
 
 # Import grit first to get local third_party modules.
 import grit  # pylint: disable=ungrouped-imports,unused-import
@@ -25,8 +28,24 @@ from grit.format import data_pack
 
 
 def _RepackMain(args):
-  data_pack.RePack(args.output_pak_file, args.input_pak_files, args.whitelist,
-                   args.suppress_removed_key_output)
+  output_info_filepath = args.output_pak_file + '.info'
+  if args.compress:
+    # If the file needs to be compressed, call RePack with a tempfile path,
+    # then compress the tempfile to args.output_pak_file.
+    temp_outfile = tempfile.NamedTemporaryFile()
+    out_path = temp_outfile.name
+    # Strip any non .pak extension from the .info output file path.
+    splitext = os.path.splitext(args.output_pak_file)
+    if splitext[1] != '.pak':
+      output_info_filepath = splitext[0] + '.info'
+  else:
+    out_path = args.output_pak_file
+  data_pack.RePack(out_path, args.input_pak_files, args.whitelist,
+                   args.suppress_removed_key_output,
+                   output_info_filepath=output_info_filepath)
+  if args.compress:
+    with gzip.open(args.output_pak_file, 'wb') as output_pak_file:
+      shutil.copyfileobj(temp_outfile, output_pak_file)
 
 
 def _ExtractMain(args):
@@ -140,6 +159,8 @@ def main():
       help='Path to a whitelist used to filter output pak file resource IDs.')
   sub_parser.add_argument('--suppress-removed-key-output', action='store_true',
       help='Do not log which keys were removed by the whitelist.')
+  sub_parser.add_argument('--compress', dest='compress', action='store_true',
+      default=False, help='Compress output_pak_file using gzip.')
   sub_parser.set_defaults(func=_RepackMain)
 
   sub_parser = sub_parsers.add_parser('extract', help='Extracts pak file')

tools/grit/repack.gni

@@ -20,6 +20,9 @@ import("//tools/grit/grit_rule.gni")
 #       Path of the file in the application bundle, defaults to
 #       {{bundle_resources_dir}}/{{source_file_part}}.
 #
+#   compress  [optional]
+#       Gzip the resulting bundle (and append .gz to the output name).
+#
 #   deps  [optional]
 #   public_deps  [optional]
 #   visibility  [optional]
@@ -32,6 +35,8 @@ template("repack") {
     _repack_target_name = "${target_name}__repack"
   }
 
+  _compress = defined(invoker.compress) && invoker.compress
+
   action(_repack_target_name) {
     forward_variables_from(invoker,
                            [
@@ -66,6 +71,9 @@ template("repack") {
     }
     args += [ rebase_path(invoker.output, root_build_dir) ]
     args += rebase_path(invoker.sources, root_build_dir)
+    if (_compress) {
+      args += [ "--compress" ]
+    }
   }
 
   if (_copy_data_to_bundle) {
@@ -153,6 +161,7 @@ template("repack_locales") {
                              [
                                "copy_data_to_bundle",
                                "bundle_output",
+                               "compress",
                                "deps",
                                "repack_whitelist",
                                "testonly",