Add deferred texture upload API.

src/core/SkPixmap.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorPriv.h"
 #include "SkConfig8888.h"
 #include "SkData.h"
@@ skipping 269 matching lines @@
 }
 
 //////////////////////////////////////////////////////////////////////////////////////////////////
 
 SkAutoPixmapStorage::SkAutoPixmapStorage() : fStorage(nullptr) {}
 
 SkAutoPixmapStorage::~SkAutoPixmapStorage() {
     this->freeStorage();
 }
 
+size_t SkAutoPixmapStorage::AllocSize(const SkImageInfo& info, size_t* rowBytes) {
+    size_t rb = info.minRowBytes();
+    if (rowBytes) {
+        *rowBytes = rb;
+    }
+    return info.getSafeSize(rb);
+}
+
 bool SkAutoPixmapStorage::tryAlloc(const SkImageInfo& info) {
     this->freeStorage();
-    
-    size_t rb = info.minRowBytes();
-    size_t size = info.getSafeSize(rb);
+
+    size_t rb;
+    size_t size = AllocSize(info, &rb);
     if (0 == size) {
         return false;
     }
     void* pixels = sk_malloc_flags(size, 0);
     if (nullptr == pixels) {
         return false;
     }
     this->reset(info, pixels, rb);
     fStorage = pixels;
     return true;
 }
 
 void SkAutoPixmapStorage::alloc(const SkImageInfo& info) {
     if (!this->tryAlloc(info)) {
         sk_throw();
     }
 }
 
 const SkData* SkAutoPixmapStorage::detachPixelsAsData() {
     if (!fStorage) {
         return nullptr;
     }
 
     const SkData* data = SkData::NewFromMalloc(fStorage, this->getSafeSize());
     fStorage = nullptr;
     this->INHERITED::reset();
 
     return data;
 }