Fix merge crop rect computation.

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 "SkBlurImageFilter.h"
@@ skipping 624 matching lines @@
 
     SkRect boundsSrc = SkRect::MakeWH(SkIntToScalar(100), SkIntToScalar(100));
     SkRect expectedBounds = SkRect::MakeXYWH(
         SkIntToScalar(-6), SkIntToScalar(-6), SkIntToScalar(112), SkIntToScalar(112));
     SkRect boundsDst = SkRect::MakeEmpty();
     composedFilter->computeFastBounds(boundsSrc, &boundsDst);
 
     REPORTER_ASSERT(reporter, boundsDst == expectedBounds);
 }
 
+DEF_TEST(ImageFilterMergeResultSize, reporter) {
+    SkBitmap greenBM;
+    greenBM.allocN32Pixels(20, 20);
+    greenBM.eraseColor(SK_ColorGREEN);
+    SkAutoTUnref<SkImage> greenImage(SkImage::NewFromBitmap(greenBM));
+    SkAutoTUnref<SkImageFilter> source(SkImageSource::Create(greenImage.get()));
+    SkAutoTUnref<SkImageFilter> merge(SkMergeImageFilter::Create(source.get(), source.get()));
+
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(1, 1);
+    bitmap.eraseColor(0);
+    const SkImageInfo info = SkImageInfo::MakeN32Premul(100, 100);
+    const SkSurfaceProps props(SkSurfaceProps::kLegacyFontHost_InitType);
+    SkAutoTUnref<SkBaseDevice> device(SkBitmapDevice::Create(info, props));
+    SkImageFilter::DeviceProxy proxy(device);
+    SkImageFilter::Context ctx(SkMatrix::I(), SkIRect::MakeXYWH(0, 0, 100, 100), nullptr,
+                               SkImageFilter::kApprox_SizeConstraint);
+    SkBitmap result;
+    SkIPoint offset;
+    REPORTER_ASSERT(reporter, merge->filterImage(&proxy, bitmap, ctx, &result, &offset));
+    REPORTER_ASSERT(reporter, result.width() == 20 && result.height() == 20);
+}
+
 static void draw_blurred_rect(SkCanvas* canvas) {
     SkAutoTUnref<SkImageFilter> filter(SkBlurImageFilter::Create(SkIntToScalar(8), 0));
     SkPaint filterPaint;
     filterPaint.setColor(SK_ColorWHITE);
     filterPaint.setImageFilter(filter);
     canvas->saveLayer(nullptr, &filterPaint);
     SkPaint whitePaint;
     whitePaint.setColor(SK_ColorWHITE);
     canvas->drawRect(SkRect::Make(SkIRect::MakeWH(4, 4)), whitePaint);
     canvas->restore();
@@ skipping 648 matching lines @@
                                                          SkSurface::kNo_Budgeted,
                                                          SkImageInfo::MakeN32Premul(1, 1),
                                                          0,
                                                          &props,
                                                          SkGpuDevice::kUninit_InitContents));
     SkImageFilter::DeviceProxy proxy(device);
 
     test_negative_blur_sigma(&proxy, reporter);
 }
 #endif