Implement HitTestAggregator

components/viz/hit_test/BUILD.gn

+# 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.
+
+import("//testing/test.gni")
+
+component("hit_test") {
+  defines = [ "HIT_TEST_IMPLEMENTATION" ]
+
+  sources = [
+    "display_hit_test_data.h",
+    "display_hit_test_data_factory.h",
+    "display_hit_test_data_factory_local.cc",
+    "display_hit_test_data_factory_local.h",
+    "hit_test_aggregator.cc",
+    "hit_test_aggregator.h",
+  ]
+
+  deps = [
+    "//cc/ipc:interfaces",
+    "//components/viz/hit_test/public/interfaces",
+  ]
+}
+
+# These are part of the components_unittests build target.
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "hit_test_aggregator_unittest.cc",
+  ]
+
+  deps = [
+    ":hit_test",
+    "//base",
+    "//base/test:run_all_unittests",
+    "//base/test:test_support",
+    "//components/viz/hit_test/public/interfaces",
+    "//testing/gtest",
+  ]
+}