move GrMalloc, GrFree, Gr_bzero to their sk equivalents

BUG=
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/23566022

git-svn-id: http://skia.googlecode.com/svn/trunk@11486 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrPlotMgr.h b/src/gpu/GrPlotMgr.h
index 3aa8cf6..6ea6086 100644
--- a/src/gpu/GrPlotMgr.h
+++ b/src/gpu/GrPlotMgr.h
@@ -32,7 +32,7 @@
     }
 
     void reset() {
-        Gr_bzero(fBusy, fDim.fX * fDim.fY);
+        sk_bzero(fBusy, fDim.fX * fDim.fY);
     }
 
     bool newPlot(GrIPoint16* loc) {