Revert of Revert of allow canvas to force conservative clips (for speed) (patchset #1 id:1 of https://codereview.chromium.org/554033003/)

Reason for revert:
May just rebaseline, plus want to see the results of the chrome tests, so re-trying this CL.

Original issue's description:
> Revert of allow canvas to force conservative clips (for speed) (patchset #7 id:120001 of https://codereview.chromium.org/541593005/)
>
> Reason for revert:
> multipicturedraw failed on nvprmsaa -- don't know why yet
>
> Original issue's description:
> > Allow SkCanvas to be initialized to force conservative rasterclips. This has the following effects:
> >
> > 1. Queries to the current clip will be conservatively large. This can mean the quickReject may return false more often.
> >
> > 2. The conservative clips mean less work is done.
> >
> > 3. Enabled by default for Gpu, Record, and NoSaveLayer canvases.
> >
> > 4. API is private for now.
> >
> > Committed: https://skia.googlesource.com/skia/+/27a5e656c3d6ef22f9cb34de18e1b960da3aa241
>
> TBR=robertphillips@google.com,bsalomon@google.com,mtklein@google.com,junov@google.com
> NOTREECHECKS=true
> NOTRY=true
>
> Committed: https://skia.googlesource.com/skia/+/6f09709519b79a1159f3826645f1c5fbc101ee11

R=robertphillips@google.com, bsalomon@google.com, mtklein@google.com, junov@google.com, reed@google.com
TBR=bsalomon@google.com, junov@google.com, mtklein@google.com, reed@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/560713002
diff --git a/include/utils/SkNoSaveLayerCanvas.h b/include/utils/SkNoSaveLayerCanvas.h
index 686f179..56a0962 100644
--- a/include/utils/SkNoSaveLayerCanvas.h
+++ b/include/utils/SkNoSaveLayerCanvas.h
@@ -16,7 +16,8 @@
 // It also simplifies the clipping calls to only use rectangles.
 class SK_API SkNoSaveLayerCanvas : public SkCanvas {
 public:
-    SkNoSaveLayerCanvas(SkBaseDevice* device) : INHERITED(device) {}
+    SkNoSaveLayerCanvas(SkBaseDevice* device) : INHERITED(device, kConservativeRasterClip_InitFlag)
+    {}
 
 protected:
     virtual SaveLayerStrategy willSaveLayer(const SkRect* bounds, const SkPaint* paint,
@@ -25,21 +26,6 @@
         return kNoLayer_SaveLayerStrategy;
     }
 
-    // disable aa for speed
-    virtual void onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->INHERITED::onClipRect(rect, op, kHard_ClipEdgeStyle);
-    }
-
-    // for speed, just respect the bounds, and disable AA. May give us a few
-    // false positives and negatives.
-    virtual void onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->updateClipConservativelyUsingBounds(path.getBounds(), op,
-                                                  path.isInverseFillType());
-    }
-    virtual void onClipRRect(const SkRRect& rrect, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->updateClipConservativelyUsingBounds(rrect.getBounds(), op, false);
-    }
-
 private:
     typedef SkCanvas INHERITED;
 };