cc: Add some unit tests for readbacks outside of the viewport.

cc/trees/layer_tree_host_pixeltest_readback.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "build/build_config.h"
 #include "cc/layers/content_layer.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/test/layer_tree_pixel_test.h"
 #include "cc/test/paths.h"
@@ skipping 798 matching lines @@
   device_viewport_copy_subrect_ = gfx::Rect(50, 50, 100, 100);
   device_scale_factor_ = 2.f;
 
   RunPixelTestWithReadbackTarget(GL_WITH_DEFAULT,
                                  background,
                                  green.get(),
                                  base::FilePath(FILE_PATH_LITERAL(
                                      "green_small_with_blue_corner.png")));
 }
 
+TEST_F(LayerTreeHostReadbackPixelTest, ReadbackNonRootLayerOutsideViewport) {
+  scoped_refptr<SolidColorLayer> background = CreateSolidColorLayer(
+      gfx::Rect(200, 200), SK_ColorWHITE);
+
+  scoped_refptr<SolidColorLayer> green = CreateSolidColorLayer(
+      gfx::Rect(200, 200), SK_ColorGREEN);
+  // Only the top left quarter of the layer is inside the viewport, so the
+  // blue layer is entirely outside.
+  green->SetPosition(gfx::Point(100, 100));
+  background->AddChild(green);
+
+  scoped_refptr<SolidColorLayer> blue = CreateSolidColorLayer(
+      gfx::Rect(150, 150, 50, 50), SK_ColorBLUE);
+  green->AddChild(blue);
+
+  RunPixelTestWithReadbackTarget(GL_WITH_DEFAULT,
+                                 background,
+                                 green.get(),
+                                 base::FilePath(FILE_PATH_LITERAL(
+                                     "green_with_blue_corner.png")));
+}
+
 }  // namespace
 }  // namespace cc
 
 #endif  // OS_ANDROID