Bench : Unused parameters cleanup

I removed unused parameters in bench wherever it was trivial to do so.
Review URL: https://codereview.appspot.com/7411046

git-svn-id: http://skia.googlecode.com/svn/trunk@7988 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/bench/MemoryBench.cpp b/bench/MemoryBench.cpp
index ab9c07d..3dff98f 100644
--- a/bench/MemoryBench.cpp
+++ b/bench/MemoryBench.cpp
@@ -31,7 +31,7 @@
         return fName.c_str();
     }
 
-    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+    virtual void onDraw(SkCanvas*) SK_OVERRIDE {
         size_t inc = fMinSize >> 4;
         SkASSERT(inc > 0);
         size_t total = fMinSize * 64;