Enable Zip Archiver for unpacking by default.

Zip Archiver is a new component extension that handles zipping and
unzipping. After this change, Files app. will use Zip Archiver for
unzipping zip files. It will also allow to unzip a zip file in the
Google Drive volume or other non-local places.

Bug: 783200
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I3851c8c801d58a7573632e664b4fc2fca92acb83
Reviewed-on: https://chromium-review.googlesource.com/758696Reviewed-by: Naoki Fukino <fukino@chromium.org>
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515487}

chromeos/chromeos_switches.cc

@@ -624,9 +624,9 @@ bool IsVoiceInteractionEnabled() {
 }
 
 bool IsZipArchiverUnpackerEnabled() {
-  // Disabled by default.
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-      kEnableZipArchiverUnpacker);
+  // Enabled by default.
+  return !base::CommandLine::ForCurrentProcess()->HasSwitch(
+      kDisableZipArchiverUnpacker);
 }
 
 }  // namespace switches

ui/file_manager/file_manager/foreground/js/file_tasks.js

@@ -182,10 +182,10 @@ FileTasks.create = function(
       if (!FileTasks.zipArchiverUnpackerEnabledPromise_) {
         FileTasks.zipArchiverUnpackerEnabledPromise_ =
             new Promise(function(resolve, reject) {
-              // Disabled by default.
+              // Enabled by default.
               chrome.commandLinePrivate.hasSwitch(
-                  'enable-zip-archiver-unpacker', function(enabled) {
-                    resolve(enabled);
+                  'disable-zip-archiver-unpacker', function(disabled) {
+                    resolve(!disabled);
                   });
             });
       }