Speculative fix for uninitialized bitmap mem in ImageFilterTest

tests/ImageFilterTest.cpp

 /*
  * Copyright 2013 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 "SkBitmapDevice.h"
 #include "SkBitmapSource.h"
@@ skipping 1211 matching lines @@
     SkAutoTUnref<SkImageFilter> filter(SkImageSource::Create(image));
 
     SkAutoTUnref<SkData> data(SkValidatingSerializeFlattenable(filter));
     SkAutoTUnref<SkFlattenable> flattenable(SkValidatingDeserializeFlattenable(
         data->data(), data->size(), SkImageFilter::GetFlattenableType()));
     SkImageFilter* unflattenedFilter = static_cast<SkImageFilter*>(flattenable.get());
     REPORTER_ASSERT(reporter, unflattenedFilter);
 
     SkBitmap bm;
     bm.allocN32Pixels(10, 10);
+    bm.eraseColor(SK_ColorBLUE);
     SkPaint paint;
     paint.setColor(SK_ColorRED);
     paint.setImageFilter(unflattenedFilter);
 
     SkCanvas canvas(bm);
     canvas.drawRect(SkRect::MakeWH(10, 10), paint);
     REPORTER_ASSERT(reporter, *bm.getAddr32(0, 0) == SkPreMultiplyColor(SK_ColorGREEN));
 }
 
 #if SK_SUPPORT_GPU
@@ skipping 63 matching lines @@
                                                          SkSurface::kNo_Budgeted,
                                                          SkImageInfo::MakeN32Premul(1, 1),
                                                          0,
                                                          &props,
                                                          SkGpuDevice::kUninit_InitContents));
     SkImageFilter::Proxy proxy(device);
 
     test_negative_blur_sigma(&proxy, reporter);
 }
 #endif