Fix issue with sync status observer for testshell.

Also adds a test to ensure the sync status observer behaves correctly.

Depends on: https://codereview.chromium.org/23686014/

BUG=272584

Review URL: https://codereview.chromium.org/23450036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228237 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228237
Inflating bounds for rotation should support min/max progress

These values were previously assumed to be 0 and 1 (the parameters were ignored).

R=ajuma@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/26869008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228238 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228238