Implement HitTestAggregator

services/viz/public/interfaces/hit_test_region_list.mojom

Index: services/viz/public/interfaces/hit_test_region_list.mojom
diff --git a/services/viz/public/interfaces/hit_test_region_list.mojom b/services/viz/public/interfaces/hit_test_region_list.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..1b9e0b7fa5de2081fddbc8972bec3d5151069b5a
--- /dev/null
+++ b/services/viz/public/interfaces/hit_test_region_list.mojom
@@ -0,0 +1,59 @@
+// 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.
+
+module viz.hit_test.mojom;
+
+import "cc/ipc/surface_id.mojom";
+import "ui/gfx/geometry/mojo/geometry.mojom";
+import "ui/gfx/mojo/transform.mojom";
+
+// Region maps to this surface (me).
+const uint32 kHitTestMine = 0x01;

[danakj, 2017/06/30 20:39:38]

I think these should be defined in the C++ and then mirrored/included into the
mojom. These to me are like data types for instance gfx::Rect. We have a C++
type, which we can refer to, and a mojom which represents it. This is simpler as
its constants but same idea I think. That would put them in viz/common, which is
where there is C++ referring to them also, and resolves my feelings about
viz/common->services/viz/public/interfaces. WDYT Rob?

Put another way, since C++ types are referring to these (abstractly atm) in
viz/common/, we should put these in the C++ in viz/common/?

[gklassen, 2017/07/12 14:43:51]

Acknowledged.

+
+// Region ignored for hit testing (transparent backgrounds & hover:none).
+const uint32 kHitTestIgnore = 0x02;
+
+// Region maps to child surface (OOPIF).
+const uint32 kHitTestChildSurface = 0x04;
+
+// Irregular boundary - send HitTestRequest to resolve.
+const uint32 kHitTestAsk = 0x08;
+
+// Touch event handler exists.
+const uint32 kHitTestTouchEventHandler = 0x10;
+
+struct HitTestRegion {
+  // Flags to indicate the type of HitTestRegion.
+  uint32 flags;
+
+  // SurfaceId is required when flags = kHitTestChildSurface.
+  cc.mojom.SurfaceId surface_id;
+
+  // The rect of the region in the coordinate space of the embedder.
+  gfx.mojom.Rect rect;
+
+  // The transform of the region.  The transform applied to the rect
+  // defines the space occupied by this region in the coordinate space of
+  // the embedder.
+  gfx.mojom.Transform transform;
+};
+
+struct HitTestRegionList {
+  // SurfaceId corresponding to this HitTestData.
+  cc.mojom.SurfaceId surface_id;
+
+  // Flags indicate how to handle events that match no sub-regions.
+  // kHitTestMine routes un-matched events to this surface (opaque).
+  // kHitTestIgnore keeps previous match in the parent (transparent).
+  uint32 flags;
+
+  // The bounds of the surface.
+  gfx.mojom.Rect bounds;
+
+  // The transform applied to all regions in this surface.
+  gfx.mojom.Transform transform;
+
+  // The list of sub-regions in front to back order.
+  array<HitTestRegion> regions;
+};