[views-mus] Support custom cursors.

services/ui/public/interfaces/cursor/cursor_struct_traits_unittest.cc

 // Copyright 2017 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 "services/ui/public/interfaces/cursor/cursor_struct_traits.h"
 
 #include "base/message_loop/message_loop.h"
 #include "mojo/common/common_custom_types_struct_traits.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "services/ui/public/interfaces/cursor/cursor.mojom.h"
@@ skipping 81 matching lines @@
 
     for (int x = 0; x < input.cursor_frames()[f].width(); ++x) {
       for (int y = 0; y < input.cursor_frames()[f].height(); ++y) {
         EXPECT_EQ(input.cursor_frames()[f].getColor(x, y),
                   output.cursor_frames()[f].getColor(x, y));
       }
     }
   }
 }
 
+// Test that we deal with empty bitmaps. (When a cursor resource isn't loaded
+// in the renderer, the renderer will send a kCurstomCursor with an empty
+// bitmap.)
+TEST_F(CursorStructTraitsTest, TestEmptyCursor) {
+  const base::TimeDelta kFrameDelay = base::TimeDelta::FromMilliseconds(15);
+  const gfx::Point kHotspot = gfx::Point(5, 2);
+  const float kScale = 2.0f;
+
+  ui::CursorData input(kHotspot, {SkBitmap()}, kScale, kFrameDelay);
+
+  ui::CursorData output;
+  ASSERT_TRUE(EchoCursorData(input, &output));

[sky, 2017/04/26 22:16:15]

optional: you don't need to route through mojom to test serialization. See
https://groups.google.com/a/chromium.org/forum/#!searchin/chromium-mojo/trait...
.

[Elliot Glaysher, 2017/04/26 23:09:04]

I'm confused. Isn't that what I'm doing here? This calls the
mojom::Deserialize(mojom::Serialize()) pattern wrapped in EchoCursorData().

[sky, 2017/04/26 23:35:01]

Indeed you are. I was confused by the name. Sorry.

+
+  ASSERT_EQ(1u, output.cursor_frames().size());
+  EXPECT_TRUE(output.cursor_frames().front().empty());
+}
+
 }  // namespace ui