add legacy/helper allocN32Pixels, and convert gm to use it

include/core/SkBitmap.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBitmap_DEFINED
 #define SkBitmap_DEFINED
 
@@ skipping 249 matching lines @@
     
     /**
      *  Allocate a pixelref to match the specified image info, using the default
      *  allocator.
      *  On success, the bitmap's pixels will be "locked", and return true.
      *  On failure, the bitmap will be set to empty and return false.
      */
     bool allocPixels(const SkImageInfo& info) {
         return this->allocPixels(info, NULL, NULL);
     }
-    
+
+    /**
+     *  Legacy helper function, which creates an SkImageInfo from the specified
+     *  config and then calls allocPixels(info).
+     */
+    bool allocConfigPixels(Config, int width, int height, bool isOpaque = false);
+
+    bool allocN32Pixels(int width, int height, bool isOpaque = false) {
+        SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
+        if (isOpaque) {
+            info.fAlphaType = kOpaque_SkAlphaType;
+        }
+        return this->allocPixels(info);
+    }
+
     /**
      *  Install a pixelref that wraps the specified pixels and rowBytes, and
      *  optional ReleaseProc and context. When the pixels are no longer
      *  referenced, if ReleaseProc is not null, it will be called with the
      *  pixels and context as parameters.
      *  On failure, the bitmap will be set to empty and return false.
      */
     bool installPixels(const SkImageInfo&, void* pixels, size_t rowBytes,
                        void (*ReleaseProc)(void* addr, void* context),
                        void* context);
@@ skipping 576 matching lines @@
 
 inline SkPMColor SkBitmap::getIndex8Color(int x, int y) const {
     SkASSERT(fPixels);
     SkASSERT(fConfig == kIndex8_Config);
     SkASSERT((unsigned)x < fWidth && (unsigned)y < fHeight);
     SkASSERT(fColorTable);
     return (*fColorTable)[*((const uint8_t*)fPixels + y * fRowBytes + x)];
 }
 
 #endif