alternate ntp: tweaks and fixes for bookmark bar in ntp

alternate ntp: tweaks and fixes for bookmark bar in ntp

- change bmb height to 48
- paint separator above bmb with different colors for standard and theme
- bmb background
  * if theme is used, paint theme background color at max 80% opacity
  * otherwise, use transparent background
- only show bmb when at least a row of "Most Visited" thumbnails is shown
- don't show instruction bmb
- fix new tab css to let content view show entire theme background image with no
  vertical offset, 'cos floating detached bmb doesn't show any part of the image
- fix to paint separator below bmb after a suggestion is committed

BUG=158944
TEST=verify per bug rpt


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=165963

[kuan, 2012-11-02 23:16:18]

this cl has multiple tweaks and fixes, all detailed in cl description.

sky, pls look at everything.
perdo, fyi, i changed bmb height.

thx.

[kuan, 2012-11-02 23:16:44]

evan, pls look at ntp_resource_cache.cc.  thx.

[Evan Stade, 2012-11-03 00:46:37]

lgtm

[sky, 2012-11-05 15:22:36]

LGTM

[commit-bot: I haz the power, 2012-11-05 15:48:02]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/kuan@chromium.org/11365075/1

[commit-bot: I haz the power, 2012-11-05 18:24:03]

Change committed as 165963