Fix the issue in 'Clear browsing data' dialog with Cancel vs Close button.

We should *only* save the state of the checkboxes when the user click on the button to clear the data,
otherwise we shouldn't change the preferences of the checkboxes.

Along the way, rename the button from 'Close' to 'Cancel'.

BUG=35098
TEST=open the dialog, see the current state of the checkboxes, click 'Cancel'.
reopen the dialog, the state should be the same. Now uncheck some checkbox,
click 'Cancel', reopen the dialog the unchecked checkbox should be checked.
Open the dialog again, uncheck a checkbox and click 'Clear browsing data',
reopen the dialog, that checkbox should be *unchecked*.

Review URL: http://codereview.chromium.org/3389033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60755 0039d316-1c4b-4281-b951-d872f2087c98