use the correct rowBytes so Debug build doesn't assert

tools/bench_playback.cpp

Index: tools/bench_playback.cpp
diff --git a/tools/bench_playback.cpp b/tools/bench_playback.cpp
index 198e1f058b91a5461cf18323743dcc8c517bc44e..b5dc57bd1d78679325daf6a11fe31efb12915612 100644
--- a/tools/bench_playback.cpp
+++ b/tools/bench_playback.cpp
@@ -28,8 +28,10 @@ static void bench(SkPMColor* scratch, SkPicture& src, const char* name) {
     SkRecorder recorder(SkRecorder::kWriteOnly_Mode, &record, src.width(), src.height());
     src.draw(&recorder);
 
-    SkAutoTDelete<SkCanvas> canvas(
-        SkCanvas::NewRasterDirectN32(src.width(), src.height(), scratch, 0));
+    SkAutoTDelete<SkCanvas> canvas(SkCanvas::NewRasterDirectN32(src.width(),
+                                                                src.height(),
+                                                                scratch,
+                                                                src.width() * sizeof(SkPMColor)));
     canvas->clipRect(SkRect::MakeWH(SkIntToScalar(FLAGS_tile), SkIntToScalar(FLAGS_tile)));
 
     const SkMSec start = SkTime::GetMSecs();