replace setConfig+allocPixels with single call

tests/ShaderOpacityTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorShader.h"
 #include "SkGradientShader.h"
 #include "SkShader.h"
 #include "Test.h"
 
 static void test_bitmap(skiatest::Reporter* reporter) {
+    SkImageInfo info = SkImageInfo::MakeN32Premul(2, 2);
+
     SkBitmap bmp;
-    bmp.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
+    bmp.setConfig(info);
 
     // test 1: bitmap without pixel data
     SkShader* shader = SkShader::CreateBitmapShader(bmp,
         SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
     REPORTER_ASSERT(reporter, shader);
     REPORTER_ASSERT(reporter, !shader->isOpaque());
     shader->unref();
 
     // From this point on, we have pixels
-    bmp.allocPixels();
+    bmp.allocPixels(info);
 
     // test 2: not opaque by default
     shader = SkShader::CreateBitmapShader(bmp,
         SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
     REPORTER_ASSERT(reporter, shader);
     REPORTER_ASSERT(reporter, !shader->isOpaque());
     shader->unref();
 
     // test 3: explicitly opaque
     bmp.setAlphaType(kOpaque_SkAlphaType);
@@ skipping 70 matching lines @@
     // since lack of opacity will depend solely on the paint
     SkColorShader colorShader4;
     REPORTER_ASSERT(reporter, colorShader4.isOpaque());
 }
 
 DEF_TEST(ShaderOpacity, reporter) {
     test_gradient(reporter);
     test_color(reporter);
     test_bitmap(reporter);
 }