WIP Hittest Component.

components/viz/hittest/hittest.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 "components/viz/hittest/hittest.h"
+
+#include "base/logging.h"
+
+namespace viz {
+
+struct Hittest::Region {

[rjkroege, 2017/05/29 15:58:02]

it's convention that stuff that never leaves the .cc should be in an anonymous
namespace

+  cc::SurfaceId surface_id;
+  gfx::QuadF quad;
+  unsigned int flags;
+  int nChildren;
+};
+
+Hittest* Hittest::instance_;
+
+Hittest::Hittest() {
+  current_regions_ = &regions_[0];
+}
+
+Hittest::~Hittest() {}
+
+cc::SurfaceId Hittest::InternalGetSurfaceIdAtPoint(
+    cc::SurfaceId root_surface_id,
+    const gfx::Point& point,
+    gfx::Point* transformed_point) {
+  return root_surface_id;
+}
+
+void Hittest::SubmitHittestData(
+    viz::hittest::mojom::HittestData& hittest_data) {
+  // add to pending
+}
+
+void Hittest::Aggregate() {

[rjkroege, 2017/05/29 15:58:02]

I'd not have the empty entry point. Write the aggregator and its unittests as
one. 

+  // todo: walk pending list and assemble into a _regions list
+  swap();
+}
+
+void Hittest::swap() {
+  if (current_regions_ == &regions_[0]) {
+    current_regions_ = &regions_[1];
+  } else {
+    current_regions_ = &regions_[0];
+  }
+}
+
+}  // namespace viz