small tidy of benchmarkstream

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/691b6af907e55250a29a7a2a346b63c2026011c3

Review URL: https://codereview.chromium.org/1395703002
diff --git a/tools/VisualBench/TimingStateMachine.h b/tools/VisualBench/TimingStateMachine.h
index 2215059..3f40b6d 100644
--- a/tools/VisualBench/TimingStateMachine.h
+++ b/tools/VisualBench/TimingStateMachine.h
@@ -38,10 +38,9 @@
     ParentEvents nextFrame(bool preWarmBetweenSamples);
 
     /*
-     * The caller should call this when they are ready to move to the next benchmark.  The caller
-     * must call this with the *last* benchmark so post draw hooks can be invoked
+     * The caller should call this when they are ready to move to the next benchmark.
      */
-    void nextBenchmark(SkCanvas*, Benchmark*);
+    void nextBenchmark();
 
     /*
      * When TimingStateMachine returns kTimingFinished_ParentEvents, then the owner can call