GitLab

We also want the "classical" NTP to coexist with the new design, and
switchable via Finch. Key changes:
- Adding classes to #ntp-content, then using CSS to control styling.
  - .classical for old NTP
  - .md for Material Design
  - .default-theme for values that will be overriden by themes. This is
    needed so dynamic CSS changes in setCustomThemeStyle() are not
    subsumed by specialized .classical and .md.
  - .dark: for dark background.
- The .mv-mask <div> is promoted to handle tile effects, including
  border, shadow, and background. Borders are drawn differently now.
  This lead to fix of 1px offset of .mv-title .

Some new designs are still in flux. Our goal is to get a reasonable bulk
committed for m38, then worry about some tune-ups later.

TEST=Run "chrome.exe --force-fieldtrials=MaterialDesignNTP/Enabled/",
visit chrome-search://local-ntp/local-ntp.html . If chrome.exe is run
without the switch, the local NTP should be identical to before, except
for 1px .mv-title shift.

BUG=400332

Review URL: https://codereview.chromium.org/473583002

Cr-Commit-Position: refs/heads/master@{#289682}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289682 0039d316-1c4b-4281-b951-d872f2087c98