[UIFe][FFe] add previews for Gwibber lens

Since this is going to impact the visible interfaces, a UIFe is needed here as well [1]. Please send email to the docs team including screen shots, and paste the link to the email in this bug.

What testing has been done to date on this? With it landing late what is the plan if there is a serious problem. Do we just disable it?

Can this feature be uploaded on its own? Would prefer it not to be combined with bug fixes, so we have an easy way of backing it out, if it proves problematic.

[1] https://wiki.ubuntu.com/FreezeExceptionProcess

Part of the change needs to land in unity and libunity, but that would not be used without the gwibber lens. So the easy way to back out the change would be to downgrade the lens version. The change to the lens itself is minimal, most of the code is in adding a new preview type to unity.

Email to ubuntu-doc:
https://lists.ubuntu.com/archives/ubuntu-doc/2012-September/016849.html

The gwibber lens still isn't installed by default, right?

In that case, +1 from the Docs Team.

Part of this is to include it by default.

Ok, I'll still give a +1. I can install the gwibber lens for the screenshots then. We won't really have any docs for this feature in particular though.

Approved. Please work with the unity team to make sure the necessary reprequisites land before beta 2 freeze.

Marking the ubuntu-docs task as invalid since there was no existing docs for this. Please reopen if needed.

This bug was fixed in the package gwibber - 3.5.90-0ubuntu2

---------------
gwibber (3.5.90-0ubuntu2) quantal-proposed; urgency=low

  * debian/patches/lp_1051801.patch
    - Fixed SIGSEGV in gwibber-service (LP: #1051801)

gwibber (3.5.90-0ubuntu1) quantal-proposed; urgency=low

  * New upstream release
    - Use Unity Previews in the lens (LP: #1049127)
    - Translate gwibber.application (LP: #1052375)
  * debian/control
    - add recommends for unity-lens-gwibber (LP: #1049127)
    - bump build dep for libunity-dev to >= 6.5.1
 -- Ken VanDine <email address hidden> Thu, 20 Sep 2012 02:51:55 -0400

This bug was fixed in the package libunity - 6.5.2-0ubuntu1

---------------
libunity (6.5.2-0ubuntu1) quantal-proposed; urgency=low

  [ Timo Jyrinki ]
  * New upstream release.
    - Added gcov code coverage tooling
    - Implemented provides_personal_content flag
    - Implemented home-lens-default-name lens property
    - Add hints parameter to dbus Activate() method
    - Added build system support for documentation generation
    - Allow passing -1 as rating value (LP: #1050464)
    - Added application category into CategoryType enum.
    - Added SocialPreview (LP: #1049127)
    - UnityLauncher: support favorites prefixes (LP: #761155)

  [ Didier Roche ]
  * debian/libunity9.symbols:
    - update symbols to include the new APIs
 -- Didier Roche <email address hidden> Thu, 20 Sep 2012 16:14:43 +0200

This bug was fixed in the package unity - 6.6.0-0ubuntu1

---------------
unity (6.6.0-0ubuntu1) quantal-proposed; urgency=low

  * New upstream release.
    - Fixes non-escaped character sequences in dash previews (LP: #1039020)
    - Updated background layer for preview cover-art and details panels
      to be 10% low-light
    - Expand a PlacesGroup if it is the only category that contains results
      (LP: #950710)
    - Update unity autopilot tests to match autopilot API
    - Updated the convert files to fix some typos in the key names
    - Add gmodule dependency
    - Activate proper result if the categories aren't displayed in-order
      (LP: #1040101)
    - Refactor device launcher icons (LP: #713423)
    - LauncherController: make the controller enable the launcher struts,
      based on hide-mode option (LP: #1044005)
    - Launcher: make always possible to drag an icon to the bottom or top
      of its sub list (LP: #1043968)
    - Don't desat bfb/hud icon in DNDReset (LP: #1043963)
    - Progressively adjust the speed of the minimize animation. First
      time it is used is slower, then speeds up the more it is used.
      (LP: #1017510)
    - Implement new ordering of categories for home lens. (LP: #1043915)
    - UnityWindow now implements ScaleWindowInterface (LP: #876017)
    - Launcher: restore an icon position after that the dragging has been
      cancelled (LP: #955561)
    - LauncherDragWindow: cancel drag on window mapped/unmapped
      (LP: #1044723)
    - Now there is a check of an override color in RefreshColor (which is
      called when a PropertyNotify event happens). Also added a check in
      FullySaturateColor to a void division by zero. (LP: #975350)
    - Queue redraw after cover-art texture is updated from a url/file source.
      (LP: #1043947)
    - Fixed ability to delete glib::Source wrapper during its callback
      (LP: #1044823)
    - Close preview when dash is hidden. (LP: #1045298)
    - LauncherModel: rewrite the Reordering functions to keep the icon
      priority deltas (LP: #761155)
    - Make sure we can pass extra hints when activating preview actions.
      (LP: #1046352)
    - UnityWindow: scale window code improved (LP: #1033935)
    - The mouse will now cause the HUD buttons to change selection
      (LP: #1042692)
    - "Alt+Space" shortcut to reveal the window menu is not hardcoded, but a
       Compiz key option. " (Hold)" should also be translated. Made all
       Compiz plug-in names and all Compiz plug-in option names in
       unityshell.cpp static constants.
    - remove unity --reset, it's not anymore really needed now that we are
      in stable days of unity and we moved to gsettings
    - Removed the variables 'oldPrev' and 'oldNext' which got assigned the
      value NULL, but then were never used
    - Fixed the size of the previews to 770x380 pixels. (LP: #1045243)
    - UnityWindow: use smart pointers, use static close_icon (with dynamic
      state) and PanelStyle context (LP: #1033935) (LP: #1045127)
      (LP: #1046124) (LP: #1046126)
    - Remove everything in the #ifndef USE_MODERN_COMPIZ_GL ifdefs and remove
      the ifdefs alltogether. unity now requires compiz...