Make the third party wallpaper syncable through different devices.

chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js

Index: chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
diff --git a/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js b/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
index eba94a343e034ee748bf9ae6095796fde5995a08..5a63f0f80898e34bed9b493a2eeef3d44eb195e2 100644
--- a/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
+++ b/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
@@ -296,11 +296,6 @@ chrome.syncFileSystem.onFileStatusChanged.addListener(function(detail) {
               Constants.CustomWallpaperThumbnailSuffix, '');
           WallpaperUtil.deleteWallpaperFromLocalFS(fileName);
         }
-      } else {  // detail.direction == 'local_to_remote'

[bshe, 2016/01/13 18:43:17]

why do you want to remove this?

[xdai1, 2016/01/14 23:03:51]

It's a different issue and it was introduced by me... I was trying to delete the
custom wallpaper if it was deleted on one device (see crbug.com/496238). And
when I worked on the current 3rd party wallpaper issue, I found that somehow I
did something useless (but also harmless). The custom wallpaper did get removed
from the local & sync file system if the device is not a powerwashed device (see
crbug.com/532278 for more detail) with or without these lines of code. I guess
something was messed up when I tested in crbug.com/496238, which made me believe
that I fixed that bug.

Anyway, Since it's unrelated to this third party wallpaper sync issue, I will
separate it into another CL. Reverted the change back.

[bshe, 2016/01/15 15:52:00]

Acknowledged.

-        if (detail.action == 'deleted') {
-          WallpaperUtil.deleteWallpaperFromSyncFS(detail.fileEntry.name);
-          WallpaperUtil.deleteWallpaperFromLocalFS(detail.fileEntry.name);
-        }
       }
     }
   });
@@ -320,6 +315,16 @@ chrome.storage.onChanged.addListener(function(changes, namespace) {
         }
       }
 
+      if (changes[Constants.AccessLocalWallpaperInfoKey]) {
+        // If the old wallpaper is a third party wallpaper we should remove it
+        // from the local & sync file system to free space.
+        var oldInfo = changes[Constants.AccessLocalWallpaperInfoKey].oldValue;
+        if (oldInfo.url.indexOf(Constants.ThirdPartyWallpaperPrefix) != -1) {
+          WallpaperUtil.deleteWallpaperFromLocalFS(oldInfo.url);
+          WallpaperUtil.deleteWallpaperFromSyncFS(oldInfo.url);
+        }
+      }
+
       if (changes[Constants.AccessSyncWallpaperInfoKey]) {
         var syncInfo = changes[Constants.AccessSyncWallpaperInfoKey].newValue;
 
@@ -368,6 +373,15 @@ chrome.storage.onChanged.addListener(function(changes, namespace) {
                               Constants.WallpaperSourceEnum.Default) {
                     chrome.wallpaperPrivate.resetWallpaper();
                   }
+
+                  // If the old wallpaper is a third party wallpaper we should
+                  // remove it from the local & sync file system to free space.
+                  if (localInfo && localInfo.url.indexOf(
+                      Constants.ThirdPartyWallpaperPrefix) != -1) {
+                    WallpaperUtil.deleteWallpaperFromLocalFS(localInfo.url);
+                    WallpaperUtil.deleteWallpaperFromSyncFS(localInfo.url);
+                  }
+
                   WallpaperUtil.saveToLocalStorage(
                       Constants.AccessLocalWallpaperInfoKey, syncInfo);
                 }
@@ -394,11 +408,20 @@ chrome.alarms.onAlarm.addListener(function() {
   SurpriseWallpaper.getInstance().next();
 });
 
-chrome.wallpaperPrivate.onWallpaperChangedBy3rdParty.addListener(function() {
+chrome.wallpaperPrivate.onWallpaperChangedBy3rdParty.addListener(function(
+    wallpaper, thumbnail, layout) {
   WallpaperUtil.saveToLocalStorage(
       Constants.AccessLocalSurpriseMeEnabledKey, false, function() {
     WallpaperUtil.saveToSyncStorage(Constants.AccessSyncSurpriseMeEnabledKey,
                                     false);
   });
   SurpriseWallpaper.getInstance().disable();
+
+  // Make third party wallpaper syncable through different devices.
+  var filename = Constants.ThirdPartyWallpaperPrefix + new Date().getTime();

[bshe, 2016/01/08 19:56:39]

We dont need a history of 3rd party wallpapers. Perhap just use the prefix as
its name? New wallpaper will override the old one. This way, we dont need to
worry about wallpapers taking too much space (especially for extensions that
change to a different wallpaper every day).

[xdai1, 2016/01/08 20:17:48]

No, I'm afraid we can't use the same file name for the third party wallpaper.
FileSystem API (http://www.html5rocks.com/en/tutorials/file/filesystem/) doesn't
provide a way to replace/override a file. I tried to use the same file name, and
when there is a new third party wallpaper, delete the old one first and then
write the new one. But it's very very flaky. Sometime it succeeds, sometime it
fails. Definitely not a good approach.

Actually in my approach here, it does only save one third party wallpaper. The
old third party wallpaper is deleted in line 318-327 or line 376-384. Because
whenever the wallpaper is changed (either by third party app, or by our built-in
app), the chrome.storage.onChanged will be triggered. And we could just check to
see if the old wallpaper is a third party wallpaper, and if it is, we just
delete it from local & sync file system to free space. I've tested on several
devices on various ways and I'm pretty sure that at most one third party
wallpaper is stored in the local & sync file system.

+  var thumbnailFilename = filename + Constants.CustomWallpaperThumbnailSuffix;
+  WallpaperUtil.storeWallpaperToSyncFS(filename, wallpaper);
+  WallpaperUtil.storeWallpaperToSyncFS(thumbnailFilename, thumbnail);

[bshe, 2016/01/13 18:43:17]

why do we want thumbnail for 3rd party wallpaper?  We aren't suppose to show it
in our wallpaper picker, right?

[xdai1, 2016/01/14 23:03:51]

You're right. Ideally we should not show the third party wallpaper in the
wallpaper picker. Instead we should show the CurrentWallpaperSetByMessage: "The
current wallpaper is set by ***, you may need to uninstall *** before selecting
a different wallpaper."

However, in this CL it just treats the third party wallpaper as a regular custom
wallpaper. In the synced device (not the device that set the third party
wallpaper), the synced third party wallpaper will show in the built-in wallpaper
picker (which is wrong). The reason is we need to sync the third-party app name
in order to do that and probably introduce new UMA for the third party wallpaper
and it might require non-trival change, which I don't want to mess up with this
CL. I plan to address this in a following up CL. Is that OK?

[bshe, 2016/01/15 15:52:00]

I might not understand you correctly, But the 3rd party app name should be
synced
as a part of user's profile if I remember correctly. Was it not get synced
somehow
and we need a new way to sync it?
But anyway, I am fine with leave it in a following up CL. But please add a TODO
so
that we dont forget. Thanks.

+  WallpaperUtil.saveWallpaperInfo(filename, layout,
+                                  Constants.WallpaperSourceEnum.Custom);
 });