make allocPixels throw on failure

tests/DrawBitmapRectTest.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 "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkData.h"
@@ skipping 172 matching lines @@
     matrix.setAll(-119.34097f,
                   -43.436558f,
                   93489.945f,
                   43.436558f,
                   -119.34097f,
                   123.98426f,
                   0, 0, SK_Scalar1);
     c.concat(matrix);
 
     SkBitmap bm;
-    bm.allocN32Pixels(width, height);
+    if (bm.tryAllocN32Pixels(width, height)) {
+        // allow this to fail silently, to test the code downstream
+    }
     bm.eraseColor(SK_ColorRED);
 
     matrix.setAll(0.0078740157f,
                   0,
                   SkIntToScalar(249),
                   0,
                   0.0078740157f,
                   SkIntToScalar(239),
                   0, 0, SK_Scalar1);
     SkShader* s = SkShader::CreateBitmapShader(bm, SkShader::kRepeat_TileMode,
@@ skipping 106 matching lines @@
 
     // ensure that we draw nothing if srcR does not intersect the bitmap
     REPORTER_ASSERT(reporter, check_for_all_zeros(dst));
 
     test_nan_antihair();
     test_giantrepeat_crbug118018(reporter);
 
     test_treatAsSprite(reporter);
     test_faulty_pixelref(reporter);
 }