Clean up SimpleIndexFile interface and implementation.
Some methods lacked comments, the .cc order was not the same as the .h
file order, and the method order didn't follow a logic that I could
follow. Now I've fixed the method order, and reordered things roughly
into a big-picture-to-little-picture order. I also added comments
describing each method, and shortened overly long comments.
I'm doing this in preparation for the generational patch; I found the
files hard to edit without this.
R=pasko
BUG=None
Review URL: https://chromiumcodereview.appspot.com/
18233014
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@210129 0039d316-1c4b-4281-b951-d872f2087c98