Implement HitTestAggregator

components/viz/hit_test/display_hit_test_data_factory.h

Index: components/viz/hit_test/display_hit_test_data_factory.h
diff --git a/components/viz/hit_test/display_hit_test_data_factory.h b/components/viz/hit_test/display_hit_test_data_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..b0ea8fef45ca4850aaa53767517f9071a73da637
--- /dev/null
+++ b/components/viz/hit_test/display_hit_test_data_factory.h
@@ -0,0 +1,33 @@
+// 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_HIT_TEST_DISPLAY_HIT_TEST_DATA_FACTORY_H_
+#define COMPONENTS_VIZ_HIT_TEST_DISPLAY_HIT_TEST_DATA_FACTORY_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <memory>
+
+#include "components/viz/hit_test/display_hit_test_data.h"
+#include "components/viz/hit_test/hit_test_export.h"
+
+namespace viz {
+namespace hit_test {
+
+class DisplayHitTestDataFactory {
+ public:
+  virtual ~DisplayHitTestDataFactory() = default;

[rjkroege, 2017/06/15 21:58:44]

you'll need to override it anyway so = 0?

[gklassen, 2017/06/16 21:49:38]

Done.

+
+  // Creates the memory required for a DisplayHitTestData structure.

[rjkroege, 2017/06/15 21:58:43]

The same pattern of abstract interface permits not worrying about how messages
will be sent to the host to coordinate the buffer swap. Either a separate class
or this one renamed. "HitTestHostClient" or something like that.

[gklassen, 2017/06/16 21:49:38]

Not sure what this is referring to?  ( sorry ). 

+  // This may use an implementation that allocates local heap memory
+  // when viz and browser are in the same process and must use an
+  // implementation that allocates shared memory when they are not.
+  virtual DisplayHitTestData* Create(int byte_count) = 0;
+};
+
+}  // namespace hit_test
+}  // namespace viz
+
+#endif  //  COMPONENTS_VIZ_HIT_TEST_DISPLAY_HIT_TEST_DATA_FACTORY_H_