erase bitmap to make valgrind happier

tests/ScaledImageCache.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 #include "SkGraphics.h"
 #include "SkCanvas.h"
 
 static const int kCanvasSize = 1;
 static const int kBitmapSize = 16;
 static const int kScale = 8;
 
 static size_t test_scaled_image_cache_useage() {
     SkAutoTUnref<SkCanvas> canvas(
             SkCanvas::NewRasterN32(kCanvasSize, kCanvasSize));
     SkBitmap bitmap;
     SkAssertResult(bitmap.allocN32Pixels(kBitmapSize, kBitmapSize));
+    bitmap.eraseColor(0xFFFFFFFF);
     SkScalar scaledSize = SkIntToScalar(kScale * kBitmapSize);
     canvas->clipRect(SkRect::MakeLTRB(0, 0, scaledSize, scaledSize));
     SkPaint paint;
     paint.setFilterLevel(SkPaint::kHigh_FilterLevel);
     size_t bytesUsed = SkGraphics::GetImageCacheBytesUsed();
     canvas->drawBitmapRect(bitmap,
                            SkRect::MakeLTRB(0, 0, scaledSize, scaledSize),
                            &paint);
     return SkGraphics::GetImageCacheBytesUsed() - bytesUsed;
 }
@@ skipping 21 matching lines @@
 
     SkGraphics::SetImageCacheByteLimit(0); // clear cache
     SkGraphics::SetImageCacheByteLimit(2 * size);
     SkGraphics::SetImageCacheSingleAllocationByteLimit(size / 2);
 
     REPORTER_ASSERT(reporter, 0 == test_scaled_image_cache_useage());
 
     SkGraphics::SetImageCacheSingleAllocationByteLimit(originalAllocationLimit);
     SkGraphics::SetImageCacheByteLimit(originalByteLimit);
 }