Fix MESA cruft appearing in 8888 vs. gpu telemetry runs

tools/PictureRenderer.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "PictureRenderer.h"
 #include "picture_utils.h"
 #include "SamplePipeControllers.h"
@@ skipping 160 matching lines @@
             canvas = SkNEW_ARGS(SkCanvas, (device.get()));
             break;
         }
 #endif
         default:
             SkASSERT(0);
             return NULL;
     }
     setUpFilter(canvas, fDrawFilters);
     this->scaleToScaleFactor(canvas);
+
+    // Pictures often lie about their extent (i.e., claim to be 100x100 but
+    // only ever draw to 90x100). Clear here so the undrawn portion will have
+    // a consistent color
+    canvas->clear(SK_ColorTRANSPARENT);
     return canvas;
 }
 
 void PictureRenderer::scaleToScaleFactor(SkCanvas* canvas) {
     SkASSERT(canvas != NULL);
     if (fScaleFactor != SK_Scalar1) {
         canvas->scale(fScaleFactor, fScaleFactor);
     }
 }
 
@@ skipping 751 matching lines @@
     virtual SkString getConfigNameInternal() SK_OVERRIDE {
         return SkString("picture_clone");
     }
 };
 
 PictureRenderer* CreatePictureCloneRenderer() {
     return SkNEW(PictureCloneRenderer);
 }
 
 } // namespace sk_tools