[WIP] Add Context to SkDrawLooper.

src/core/SkDrawLooper.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 "SkDrawLooper.h"
 #include "SkCanvas.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
 #include "SkRect.h"
 
 bool SkDrawLooper::canComputeFastBounds(const SkPaint& paint) {
     SkCanvas canvas;
+    uint32_t storage[kDrawLooperContextStorageLongCount];
 
-    this->init(&canvas);
+    SkDrawLooper::DrawContext* context =
+            this->init(&canvas, storage, sizeof(storage));
     for (;;) {
         SkPaint p(paint);
-        if (this->next(&canvas, &p)) {
+        if (context->next(&canvas, &p)) {
             p.setLooper(NULL);
             if (!p.canComputeFastBounds()) {
+                context->cleanup(storage);
                 return false;
             }
         } else {
             break;
         }
     }
+    context->cleanup(storage);
     return true;
 }
 
 void SkDrawLooper::computeFastBounds(const SkPaint& paint, const SkRect& src,
                                      SkRect* dst) {
     SkCanvas canvas;
+    uint32_t storage[kDrawLooperContextStorageLongCount];
 
     *dst = src;   // catch case where there are no loops
-    this->init(&canvas);
+    SkDrawLooper::DrawContext* context = this->init(
+            &canvas, storage, sizeof(storage));
     for (bool firstTime = true;; firstTime = false) {
         SkPaint p(paint);
-        if (this->next(&canvas, &p)) {
+        if (context->next(&canvas, &p)) {
             SkRect r(src);
 
             p.setLooper(NULL);
             p.computeFastBounds(r, &r);
             canvas.getTotalMatrix().mapRect(&r);
 
             if (firstTime) {
                 *dst = r;
             } else {
                 dst->join(r);
             }
         } else {
             break;
         }
     }
+    context->cleanup(storage);
 }
+
+void SkDrawLooper::DrawContext::cleanup(void* storage) {
+    if ((void*)this == storage) {
+        this->~DrawContext();
+    } else {
+        SkDELETE(this);
+    }
+}