cc: Make 1/4th default low res scale.

This patch makes the default low res scale factor be 0.25 * high res
scale factor. The reasoning is that 0.125 looks too blurry. With low
quality low res tiles in play, 0.25 should still incur a performance
penalty, but it shouldn't be too bad, and look a bit better.

BUG=268203

Review URL: https://codereview.chromium.org/22144008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226371 0039d316-1c4b-4281-b951-d872f2087c98
Docserver: when checking for the existence of an API on a branch, just look at
the filename, don't try to parse the whole JSON/IDL file unless absolutely
necessary. Halves the time it takes to run a cron (it recently regressed).

R=jyasskin@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/25627002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226372 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226371
SVN changes up to revision 226372