allow canvas to force conservative clips (for speed)

tests/PictureTest.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 "SkBBoxHierarchy.h"
 #include "SkBlurImageFilter.h"
 #include "SkCanvas.h"
@@ skipping 1552 matching lines @@
 
     SkPath invPath;
     invPath.addOval(rect1);
     invPath.setFillType(SkPath::kInverseEvenOdd_FillType);
     SkPath path;
     path.addOval(rect2);
     SkPath path2;
     path2.addOval(rect3);
     SkIRect clipBounds;
     SkPictureRecorder recorder;
-    // Minimalist test set for 100% code coverage of
-    // SkPictureRecord::updateClipConservativelyUsingBounds
+
+    // Testing conservative-raster-clip that is enabled by PictureRecord
     {
         SkCanvas* canvas = recorder.beginRecording(10, 10);
         canvas->clipPath(invPath, SkRegion::kIntersect_Op);
         bool nonEmpty = canvas->getClipDeviceBounds(&clipBounds);
         REPORTER_ASSERT(reporter, true == nonEmpty);
         REPORTER_ASSERT(reporter, 0 == clipBounds.fLeft);
         REPORTER_ASSERT(reporter, 0 == clipBounds.fTop);
         REPORTER_ASSERT(reporter, 10 == clipBounds.fBottom);
         REPORTER_ASSERT(reporter, 10 == clipBounds.fRight);
     }
@@ skipping 361 matching lines @@
 
     // The picture shares the immutable pixels but copies the mutable ones.
     REPORTER_ASSERT(r, mut.pixelRef()->unique());
     REPORTER_ASSERT(r, !immut.pixelRef()->unique());
 
     // When the picture goes away, it's just our bitmaps holding the refs.
     pic.reset(NULL);
     REPORTER_ASSERT(r, mut.pixelRef()->unique());
     REPORTER_ASSERT(r, immut.pixelRef()->unique());
 }