Gallery: Add the offset feature in the slide mode.

Gallery: Add the offset feature in the slide mode.

 * Add the keyboard handler to modify the viewport's offset values.

 * Make the viewport class generate CSS transform expressions including the
   offset value.

BUG=245926
TEST=manually
R=mtomasz@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284033

[hirono, 2014-07-17 07:16:14]

PTAL the CL? It depends on crrev.com/398263002.
Thank you!

[mtomasz, 2014-07-17 07:51:16]

lgtm with nits

https://codereview.chromium.org/398283002/diff/20001/ui/file_manager/gallery/...
File ui/file_manager/gallery/js/slide_mode.js (right):

https://codereview.chromium.org/398283002/diff/20001/ui/file_manager/gallery/...
ui/file_manager/gallery/js/slide_mode.js:871: 'Up': [0, 10], 'Down': [0, -10],
'Left': [10, 0], 'Right': [-10, 0]
nit: How about moving 10 to a constant?
nit: How about making delta a function like: getShiftDeltaForKey()? WDYT?
nit: Shall we multiply the offset with the scale? When the zoom is large, moving
by 10 pixels is very tedious. WDYT?

https://codereview.chromium.org/398283002/diff/20001/ui/file_manager/gallery/...
ui/file_manager/gallery/js/slide_mode.js:905: }
nit: break; at the end for consistency?

[hirono, 2014-07-18 04:57:26]

Thank you!

https://codereview.chromium.org/398283002/diff/20001/ui/file_manager/gallery/...
File ui/file_manager/gallery/js/slide_mode.js (right):

https://codereview.chromium.org/398283002/diff/20001/ui/file_manager/gallery/...
ui/file_manager/gallery/js/slide_mode.js:871: 'Up': [0, 10], 'Down': [0, -10],
'Left': [10, 0], 'Right': [-10, 0]
On 2014/07/17 07:51:16, mtomasz (OOO until July 22nd) wrote:
> nit: How about moving 10 to a constant?
> nit: How about making delta a function like: getShiftDeltaForKey()? WDYT?
I made the offset map constant.

> nit: Shall we multiply the offset with the scale? When the zoom is large,
moving
> by 10 pixels is very tedious. WDYT?
Done.

[hirono, 2014-07-18 04:57:28]

The CQ bit was checked by hirono@chromium.org

[commit-bot: I haz the power, 2014-07-18 04:58:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hirono@chromium.org/398283002/60001

[hirono, 2014-07-18 08:13:37]

Committed patchset #4 manually as r284033 (presubmit successful).