Add viz-host HitTestQuery.

components/viz/host/hit_test/hit_test_query.h

Index: components/viz/host/hit_test/hit_test_query.h
diff --git a/components/viz/host/hit_test/hit_test_query.h b/components/viz/host/hit_test/hit_test_query.h
new file mode 100644
index 0000000000000000000000000000000000000000..1f76c87bdd0b4d0eb24d7c0577359b36af93e0c2
--- /dev/null
+++ b/components/viz/host/hit_test/hit_test_query.h
@@ -0,0 +1,62 @@
+// 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.
+
+#ifndef COMPONENTS_VIZ_HOST_HIT_TEST_HIT_TEST_QUERY_H_
+#define COMPONENTS_VIZ_HOST_HIT_TEST_HIT_TEST_QUERY_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "components/viz/common/display_hit_test_data.h"
+#include "ui/gfx/geometry/point.h"
+
+namespace viz {
+namespace hit_test {
+
+struct Target {
+  cc::FrameSinkId id;
+  // Coordinates in the coordinate system of the target FrameSinkId.
+  gfx::Point location_in_target;
+  // Different flags are defined in services/viz/public/interfaces/
+  // hit_test_data.mojom.
+  uint32_t flags;
+};
+
+// Finds the target for a given location based on DisplayHitTestDataList
+// aggregated by HitTestComponent.
+// TODO(riajiang): Handle 3d space cases correctly.
+class HitTestQuery {
+ public:
+  HitTestQuery();
+  ~HitTestQuery();
+
+  // TODO(riajiang): Read from shmem directly once it's set up and delete this
+  // function. For now, use fake data.
+  void set_display_hit_test_data_list(
+      DisplayHitTestDataList display_hit_test_data_list) {
+    display_hit_test_data_list_ = std::move(display_hit_test_data_list);
+  }
+
+  // Finds Target for |location_in_root|, including the FrameSinkId of the
+  // target, updated location in the coordinate system of the target and
+  // hit-test flags for the target.
+  Target FindTargetForLocation(const gfx::Point& location_in_root);
+
+ private:
+  // Helper function to find |target| for |location_in_parent| in the |region|,
+  // returns true if a target is found and false otherwise. |location_in_parent|
+  // is in the coordinate space of |region|'s parent.
+  bool FindTargetInRegionForLocation(const gfx::Point& location_in_parent,
+                                     DisplayHitTestData* region,
+                                     Target* target) const;
+
+  DisplayHitTestDataList display_hit_test_data_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(HitTestQuery);
+};
+
+}  // namespace hit_test
+}  // namespace viz
+
+#endif  // COMPONENTS_VIZ_HOST_HIT_TEST_HIT_TEST_QUERY_H_