Update Chrome Launcher icons with new assets.

Update Chrome Launcher icons with new assets.

The new assets have correct colour contrast and more closely match the
Material Design spec. Affects both the classic and experimental
launcher.

The following assets were replaced:

- Microphone (hotword enabled and disabled states).
- Back button.
- Download progress bar.

BUG=457979, 456953
TBR=oshima@chromium.org

Committed: https://crrev.com/8d50b3ae887a32fa31e18a8669ff2187a41e0b76
Cr-Commit-Position: refs/heads/master@{#316947}

[Matt Giuca, 2015-02-17 23:07:33]

mgiuca@chromium.org changed reviewers:
+ calamity@chromium.org, oshima@chromium.org

[Matt Giuca, 2015-02-17 23:07:33]

Forgot to send this out the other day.

calamity: chrome/browser/ui/app_list/search/search_resource_manager.cc
oshima: png and grd files

[Matt Giuca, 2015-02-17 23:13:58]

mgiuca@chromium.org changed reviewers:
+ cpu@chromium.org, sadrul@chromium.org

[Matt Giuca, 2015-02-17 23:13:58]

sadrul: ui/resources owners.
cpu: chrome/app owners.

(oshima is OOO and this is needed for M41; I discussed this with sadrul and he
said it is OK as long as I tbr oshima.)

[sadrul, 2015-02-17 23:41:53]

/cc+ abodenha@

rs lgtm

[calamity, 2015-02-18 00:52:30]

lgtm

[Matt Giuca, 2015-02-18 01:39:00]

cpu: Would you be able to look at this asap? (We're trying to land this for
M42).

[cpu_(ooo_6.6-7.5), 2015-02-18 16:05:41]

lgtm

[Matt Giuca, 2015-02-18 23:25:17]

The CQ bit was checked by mgiuca@chromium.org

[commit-bot: I haz the power, 2015-02-18 23:27:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/931483004/1

[commit-bot: I haz the power, 2015-02-19 01:10:00]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-19 01:10:42]

Patchset 1 (id:??) landed as
https://crrev.com/8d50b3ae887a32fa31e18a8669ff2187a41e0b76
Cr-Commit-Position: refs/heads/master@{#316947}