The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5

commit 85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5
Author: Wenzhao Zang <wzang@chromium.org>
Date: Wed Mar 07 03:00:01 2018

cros: Support preview for custom wallpapers (Part I)

1) Didn't implement it using a dummy html background since we want to
   reuse code in WallpaperResizer.

2) The original idea was to create ShowPreviewWallpaper(imageSkia)
   and do not pass any other info to //ash until the user confirms the
   choice. But this approach requires lots of changes within
   wallpaper_private_api.cc. Instead, send all the info one-time and
   let //ash maintain the information until user either confirms or
   cancels the preview.

(Please see bug for the feature description.)

Screenshots:
https://goo.gl/p6KKF8

      and select an image under 'My photos'.

Bug:  818075 
Test: Turn on 'enable-new-wallpaper-picker' under chrome://flags,
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I86d2a82f0329bf0c357ee196301dcb0b1eef271f
Reviewed-on: https://chromium-review.googlesource.com/945075
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Oliver Chang <ochang@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541299}
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/accelerators/debug_commands.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/public/interfaces/wallpaper.mojom
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/wallpaper/wallpaper_controller.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/wallpaper/wallpaper_controller.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/wallpaper/wallpaper_controller_observer.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/wallpaper/wallpaper_controller_test_api.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/ash/wallpaper/wallpaper_controller_unittest.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/chromeos/extensions/wallpaper_api.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/chromeos/extensions/wallpaper_private_api.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/resources/chromeos/wallpaper_manager/css/wallpaper_manager.css
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/resources/chromeos/wallpaper_manager/main.html
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/ui/ash/test_wallpaper_controller.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/ui/ash/test_wallpaper_controller.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/ui/ash/wallpaper_controller_client.cc
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/browser/ui/ash/wallpaper_controller_client.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/common/extensions/api/wallpaper_private.json
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/test/data/chromeos/wallpaper_manager/unit_tests/api_mock.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/test/data/chromeos/wallpaper_manager/unit_tests/event_page_unittest.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/chrome/test/data/extensions/api_test/wallpaper_manager/test.js
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/extensions/browser/extension_function_histogram_value.h
[modify] https://crrev.com/85ff43370ffbe2fa3d3c2d7d4a64278d26de95d5/tools/metrics/histograms/enums.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7e6b186dec258ba6178468f4e4dc2f82b906a09d

commit 7e6b186dec258ba6178468f4e4dc2f82b906a09d
Author: Wenzhao Zang <wzang@chromium.org>
Date: Mon Mar 12 19:28:03 2018

cros: Support preview for online wallpapers

This is a follow-up to CL 945075. It uses the same logic to support
preview for online wallpapers.

Bug:  818075 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I17eaf9c554bacfee0b3075213e0936aa0f20c189
Reviewed-on: https://chromium-review.googlesource.com/949884
Reviewed-by: Emily Stark <estark@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Xiaoqian Dai (OOO 3-12) <xdai@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542565}
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/ash/public/interfaces/wallpaper.mojom
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/ash/wallpaper/wallpaper_controller.cc
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/ash/wallpaper/wallpaper_controller.h
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/ash/wallpaper/wallpaper_controller_unittest.cc
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/resources/chromeos/wallpaper_manager/js/util.js
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/ui/ash/test_wallpaper_controller.cc
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/ui/ash/test_wallpaper_controller.h
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/ui/ash/wallpaper_controller_client.cc
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/browser/ui/ash/wallpaper_controller_client.h
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/common/extensions/api/wallpaper_private.json
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/test/data/chromeos/wallpaper_manager/unit_tests/event_page_unittest.js
[modify] https://crrev.com/7e6b186dec258ba6178468f4e4dc2f82b906a09d/chrome/test/data/extensions/api_test/wallpaper_manager/test.js

Currently the preview wallpaper is blocked by the black backdrop in tablet mode.

Deleted: Screenshot from 2018-04-04 15-14-58.png 25.8 KB

	Screenshot from 2018-04-04 15-14-58.png 25.8 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6088355323ac15ee243051f88f94b065a8f975c7

commit 6088355323ac15ee243051f88f94b065a8f975c7
Author: Wenzhao Zang <wzang@chromium.org>
Date: Wed Apr 11 02:26:13 2018

cros: Disable backdrop for wallpaper picker app in preview mode

The preview wallpaper is blocked by a black backdrop in tablet mode,
on the new wallpaper picker (see #3 of the bug).

There are basically two ways to disable it:

1) (Not used) Disable backdrop based on the extension id, but it
   requires creating a new field in |AppWindow::CreateParams|, and we
   may need to hard code the extension id in a "white list" or something
   similar.

2) (This CL) Notify backdrop controller when preview mode starts. The
   drawback of this approach is: backdrop controller has to assume that
   the active window is indeed the wallpaper picker (because it's not
   feasible to create an extension id <-> aura::Window map.) This should
   be OK because |wallpaper_window_state_manager| has been using active
   window as the wallpaper picker window for a long time.

Bug:  818075 
Test: --new-wallpaper-picker --force-tablet-mode=touch_view
Change-Id: I12420b7ee83df32913820bf85038e2278f3940ac
Reviewed-on: https://chromium-review.googlesource.com/932911
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549734}
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/public/cpp/window_properties.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/public/cpp/window_properties.h
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wallpaper/wallpaper_controller.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wallpaper/wallpaper_controller_observer.h
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wallpaper/wallpaper_controller_test_api.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wallpaper/wallpaper_controller_test_api.h
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wallpaper/wallpaper_controller_unittest.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wm/workspace/backdrop_controller.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wm/workspace/backdrop_controller.h
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wm/workspace/workspace_layout_manager.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ash/wm/workspace/workspace_layout_manager_unittest.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/components/exo/client_controlled_shell_surface.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ui/aura/client/aura_constants.cc
[modify] https://crrev.com/6088355323ac15ee243051f88f94b065a8f975c7/ui/aura/client/aura_constants.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/364d26e31866bda2d98f8800721f55b838afad3d

commit 364d26e31866bda2d98f8800721f55b838afad3d
Author: Wenzhao Zang <wzang@chromium.org>
Date: Fri Jun 01 20:24:34 2018

cros: Notify wallpaper picker of decoding failure

1) Online wallpaper decoding has been moved to //ash, so in case of
   decoding failure, //ash should notify the picker to display an error
   message.

2) On a side note, we should move custom wallpaper decoding to //ash
   as well, but it's not time-critical.

3) Also changed base::Bind to base::BindOnce if possible.

Bug:  818075 
Change-Id: I973a2bd3a6b0b68ce8aaa37b4adc973c59556859
Reviewed-on: https://chromium-review.googlesource.com/1080042
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563773}
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/ash/public/interfaces/wallpaper.mojom
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/ash/wallpaper/wallpaper_controller.cc
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/ash/wallpaper/wallpaper_controller.h
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/ash/wallpaper/wallpaper_controller_unittest.cc
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/chromeos/extensions/wallpaper_private_api.h
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/ui/ash/test_wallpaper_controller.cc
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/ui/ash/test_wallpaper_controller.h
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/ui/ash/wallpaper_controller_client.cc
[modify] https://crrev.com/364d26e31866bda2d98f8800721f55b838afad3d/chrome/browser/ui/ash/wallpaper_controller_client.h