Add SkCanvasStack and update the Canvas utilities to use it.

src/utils/SkCanvasStateUtils.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvasStateUtils.h"
 
 #include "SkBitmapDevice.h"
 #include "SkCanvas.h"
-#include "SkNWayCanvas.h"
+#include "SkCanvasStack.h"
 #include "SkWriter32.h"
 
 #define CANVAS_STATE_VERSION 1
 /*
  * WARNING: The structs below are part of a stable ABI and as such we explicitly
  * use unambigious primitives (e.g. int32_t instead of an enum).
  *
  * ANY CHANGES TO THE STRUCTS BELOW THAT IMPACT THE ABI SHOULD RESULT IN AN
  * UPDATE OF THE CANVAS_STATE_VERSION. SUCH CHANGES SHOULD ONLY BE MADE IF
  * ABSOLUTELY NECESSARY!
@@ skipping 286 matching lines @@
     // check that the versions match
     if (CANVAS_STATE_VERSION != state->version) {
         SkDebugf("CreateFromCanvasState version does not match the one use to create the input");
         return NULL;
     }
 
     if (state->layerCount < 1) {
         return NULL;
     }
 
-    SkAutoTUnref<SkNWayCanvas> canvas(SkNEW_ARGS(SkNWayCanvas, (state->width, state->height)));
+    SkAutoTUnref<SkCanvasStack> canvas(SkNEW_ARGS(SkCanvasStack, (state->width, state->height)));
 
     // setup the matrix and clip on the n-way canvas
     setup_canvas_from_MC_state(state->mcState, canvas);
 
     // Iterate over the layers and add them to the n-way canvas
-    for (int i = 0; i < state->layerCount; ++i) {
+    for (int i = state->layerCount - 1; i >= 0; --i) {
         SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state->layers[i]));
         if (!canvasLayer.get()) {
             return NULL;
         }
-        canvas->addCanvas(canvasLayer.get());
+        canvas->pushCanvas(canvasLayer.get(), SkIPoint::Make(state->layers[i].x,
+                                                             state->layers[i].y));
     }
 
     return canvas.detach();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 void SkCanvasStateUtils::ReleaseCanvasState(SkCanvasState* state) {
     SkDELETE(state);
 }