Minor changes to GrFontCache system.

The main change is parameterizing the GrAtlasMgr so it can have a different sized backing texture and a different number of plots. This is in support of the saveLayer cache which has a smaller backing texture and only one plot.

R=jvanverth@google.com, bsalomon@google.com

Author: robertphillips@google.com

Review URL: https://codereview.chromium.org/217423014

git-svn-id: http://skia.googlecode.com/svn/trunk@14011 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrTextStrike_impl.h b/src/gpu/GrTextStrike_impl.h
index bc4f8dd..dcfc04a 100644
--- a/src/gpu/GrTextStrike_impl.h
+++ b/src/gpu/GrTextStrike_impl.h
@@ -57,7 +57,7 @@
         strike = this->generateStrike(scaler, key);
     } else if (strike->fPrev) {
         // Need to put the strike at the head of its dllist, since that is how
-        // we age the strikes for purging (we purge from the back of the list
+        // we age the strikes for purging (we purge from the back of the list)
         this->detachStrikeFromList(strike);
         // attach at the head
         fHead->fPrev = strike;