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

src/core/SkBitmap.cpp

 
 /*
  * Copyright 2008 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.
  */
 
 
 #include "SkBitmap.h"
@@ skipping 531 matching lines @@
                                                    releaseProc, context);
     if (!pr) {
         this->reset();
         return false;
     }
 
     this->setPixelRef(pr)->unref();
     return true;
 }
 
+bool SkBitmap::allocConfigPixels(Config config, int width, int height,
+                                 bool isOpaque) {
+    SkColorType ct;
+    if (!config_to_colorType(config, &ct)) {
+        return false;
+    }
+    
+    SkAlphaType at = isOpaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
+    if (!validate_alphaType(config, at, &at)) {
+        return false;
+    }
+
+    return this->allocPixels(SkImageInfo::Make(width, height, ct, at));
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkBitmap::freePixels() {
     // if we're gonna free the pixels, we certainly need to free the mipmap
     this->freeMipMap();
 
     if (NULL != fPixelRef) {
         if (fPixelLockCount > 0) {
             fPixelRef->unlockPixels();
         }
         fPixelRef->unref();
         fPixelRef = NULL;
@@ skipping 1141 matching lines @@
         if (NULL != uri) {
             str->appendf(" uri:\"%s\"", uri);
         } else {
             str->appendf(" pixelref:%p", pr);
         }
     }
 
     str->append(")");
 }
 #endif