De-virtualize SkCanvas save/restore.

This moves the state management logic into non-virtual SkCanvas methods,
and turns the virtuals into protected notifiers.

R=reed@google.com, robertphillips@google.com

Author: fmalita@chromium.org

Review URL: https://codereview.chromium.org/194713008

git-svn-id: http://skia.googlecode.com/svn/trunk@13776 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pipe/SkGPipeWrite.cpp b/src/pipe/SkGPipeWrite.cpp
index 43209f6..7f2f1a1 100644
--- a/src/pipe/SkGPipeWrite.cpp
+++ b/src/pipe/SkGPipeWrite.cpp
@@ -229,10 +229,6 @@
     }
 
     // overrides from SkCanvas
-    virtual int save(SaveFlags) SK_OVERRIDE;
-    virtual int saveLayer(const SkRect* bounds, const SkPaint*,
-                          SaveFlags) SK_OVERRIDE;
-    virtual void restore() SK_OVERRIDE;
     virtual bool isDrawingToLayer() const SK_OVERRIDE;
     virtual bool translate(SkScalar dx, SkScalar dy) SK_OVERRIDE;
     virtual bool scale(SkScalar sx, SkScalar sy) SK_OVERRIDE;
@@ -287,6 +283,10 @@
     bool shuttleBitmap(const SkBitmap&, int32_t slot);
 
 protected:
+    virtual void willSave(SaveFlags) SK_OVERRIDE;
+    virtual SaveLayerStrategy willSaveLayer(const SkRect*, const SkPaint*, SaveFlags) SK_OVERRIDE;
+    virtual void willRestore() SK_OVERRIDE;
+
     virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&) SK_OVERRIDE;
 
     virtual void onClipRect(const SkRect&, SkRegion::Op, ClipEdgeStyle) SK_OVERRIDE;
@@ -514,16 +514,17 @@
 #define NOTIFY_SETUP(canvas)    \
     AutoPipeNotify apn(canvas)
 
-int SkGPipeCanvas::save(SaveFlags flags) {
+void SkGPipeCanvas::willSave(SaveFlags flags) {
     NOTIFY_SETUP(this);
     if (this->needOpBytes()) {
         this->writeOp(kSave_DrawOp, 0, flags);
     }
-    return this->INHERITED::save(flags);
+
+    this->INHERITED::willSave(flags);
 }
 
-int SkGPipeCanvas::saveLayer(const SkRect* bounds, const SkPaint* paint,
-                             SaveFlags saveFlags) {
+SkCanvas::SaveLayerStrategy SkGPipeCanvas::willSaveLayer(const SkRect* bounds, const SkPaint* paint,
+                                                         SaveFlags saveFlags) {
     NOTIFY_SETUP(this);
     size_t size = 0;
     unsigned opFlags = 0;
@@ -547,21 +548,23 @@
     if (kNoSaveLayer == fFirstSaveLayerStackLevel){
         fFirstSaveLayerStackLevel = this->getSaveCount();
     }
-    // we just pass on the save, so we don't create a layer
-    return this->INHERITED::save(saveFlags);
+
+    this->INHERITED::willSaveLayer(bounds, paint, saveFlags);
+    // we don't create a layer
+    return kNoLayer_SaveLayerStrategy;
 }
 
-void SkGPipeCanvas::restore() {
+void SkGPipeCanvas::willRestore() {
     NOTIFY_SETUP(this);
     if (this->needOpBytes()) {
         this->writeOp(kRestore_DrawOp);
     }
 
-    this->INHERITED::restore();
-
-    if (this->getSaveCount() == fFirstSaveLayerStackLevel){
+    if (this->getSaveCount() - 1 == fFirstSaveLayerStackLevel){
         fFirstSaveLayerStackLevel = kNoSaveLayer;
     }
+
+    this->INHERITED::willRestore();
 }
 
 bool SkGPipeCanvas::isDrawingToLayer() const {