Some new tab ui fixes.

Some new tab ui fixes.

1) Always intialize the css cache.  Previously we were only
initializing if not in incognito mode.  If the first NTP was an
incognito page, it wouldn't be styled.

2) Small optimization in generating the HTML to avoid calling
ReplaceFirstSubstringAfterOffset which would need to move the
bytes after the placeholder.

3) Only generate the css for the incognito or normal mode.  Since
the NTP only needs one, we only need to generate one.

BUG=26228
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=30527

[tony, 2009-10-29 21:48:23]

I tried also keeping the HTML/CSS in a scoped_refptr<RefCountedBytes> instead of
std::string, but it doesn't actually save a copy unless you write directly to
it.  Generating the html/css always involves some string functions, so I wasn't
able to write directly to it.

[Elliot Glaysher, 2009-10-29 21:51:58]

Everything LGTM.

[Evan Martin, 2009-10-29 22:27:28]

http://codereview.chromium.org/344027/diff/1/3
File chrome/browser/dom_ui/new_tab_ui.cc (right):

http://codereview.chromium.org/344027/diff/1/3#newcode917
Line 917: "<!-- template data placeholder -->");
FWIW, if you want to get really anal about this, this calls strlen on the
string.  I think string::find() would work with a plain const char[].  Also
kFooBar for consts.