WIP Hittest Component.

components/viz/hit_test/hit_test_aggregator.h

Index: components/viz/hit_test/hit_test_aggregator.h
diff --git a/components/viz/hit_test/hit_test_aggregator.h b/components/viz/hit_test/hit_test_aggregator.h
new file mode 100644
index 0000000000000000000000000000000000000000..cb7896ea1fef1eb33d120e3a43e19548ecf3cf06
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+++ b/components/viz/hit_test/hit_test_aggregator.h
@@ -0,0 +1,103 @@
+// 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_HIT_TEST_AGGREGATOR_H_
+#define COMPONENTS_VIZ_HIT_TEST_HIT_TEST_AGGREGATOR_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <memory>
+
+#include "cc/surfaces/surface_id.h"
+#include "cc/surfaces/surface_observer.h"
+#include "components/viz/hit_test/display_hit_test_data.h"
+#include "components/viz/hit_test/hit_test_export.h"
+#include "components/viz/hit_test/public/interfaces/hit_test_data.mojom.h"
+#include "ui/gfx/geometry/quad_f.h"
+
+namespace viz {
+namespace hit_test {
+
+namespace test {
+class HitTestAggregatorTest;
+}
+
+// HitTest maintains maping between display regions and associated surfaces
+// in shared memory to enable efficient hit testing across processes.
+//
+// This is intended to be created in the viz or GPU process. For mus+ash this
+// will be true after the mus process split.
+
+using HitTestDataMap = std::map<cc::SurfaceId, hit_test::mojom::HitTestDataPtr>;
+
+class HIT_TEST_EXPORT HitTestAggregator : public cc::SurfaceObserver {
+ public:
+  HitTestAggregator();
+  ~HitTestAggregator();
+
+  // Called when HitTestData is submitted along with every call
+  // to SubmitCompositorFrame.  This is collected in pending_ until
+  // surfaces are aggregated and put on the display.
+  void SubmitHitTestData(hit_test::mojom::HitTestDataPtr hit_test_data);
+
+  // Called when surfaces have been aggregated.  Used to aggregate
+  // HitTestData into the tree structure in shared memory and used
+  // for event targetting.
+  void PostTaskAggregate(cc::SurfaceId display_surface_id);
+  void Aggregate(cc::SurfaceId display_surface_id);
+
+  // Called at BeginFrame to swap buffers in shared memory.
+  void Swap();
+
+  // SurfaceObserver
+  void OnSurfaceCreated(const cc::SurfaceInfo& surface_info) override {}
+  void OnSurfaceDestroyed(const cc::SurfaceId& surface_id) override {}
+  void OnSurfaceDamaged(const cc::SurfaceId& surface_id,
+                        const cc::BeginFrameAck& ack,
+                        bool* changed) override {}
+  void OnSurfaceDiscarded(const cc::SurfaceId& surface_id) override;
+  void OnSurfaceDamageExpected(const cc::SurfaceId& surface_id,
+                               const cc::BeginFrameArgs& args) override {}
+  // Called when a surface has been aggregated and added to the
+  // display frame.  HitTestData objects are held but ignored until
+  // this happens.  HitTestData for the surface is copied from pending_
+  // to active_ in this method.
+  void OnSurfaceWillDraw(const cc::SurfaceId& surface_id) override;
+
+  DisplayHitTestData* GetDisplayHitTestData();
+  DisplayHitTestRegion* GetCurrentRegions();
+
+ private:
+  friend class viz::hit_test::test::HitTestAggregatorTest;
+
+  HitTestDataMap pending_;
+  HitTestDataMap active_;
+
+  DisplayHitTestData* display_hit_test_data_;
+
+  // Allocates memory for the DisplayHitTestData Structure.

[rjkroege, 2017/06/12 18:13:01]

we discussed having some kind of injected factory thing. You chose not to do
this?

[gklassen, 2017/06/13 18:54:23]

No, I just wasn't quite done.  The most recent patch has the injected factory
thing ( I would highly value your review to see if this matches expectations or
could be improved ). 

+  void AllocateDisplayHitTestData();
+  void AllocateDisplayHitTestData(int length);
+
+  // Resize the memory for the DispalyHitTestData Structure.
+  // Copies current data and marks the structure

[rjkroege, 2017/06/12 18:13:01]

I think that we need to talk about how the shared memory implementation will
work

[gklassen, 2017/06/13 18:54:23]

Agreed.  The implementation currently seems to have the minimal necessary to
facilitate testing and in-process memory allocation and this will likely evolve
as we complete the shared memory implementation. 

+  void ResizeDisplayHitTestData(int length);
+
+  int GetBackIndex();
+
+  int Append(cc::SurfaceId surface_id, int index);
+  int Append(const hit_test::mojom::HitTestRegionPtr& region, int index);
+
+  // WeakPtr to handle the case when this object is deleted after
+  // the PostTaskAggregation call is scheduled but before invocation.
+  base::WeakPtrFactory<HitTestAggregator> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(HitTestAggregator);
+};
+
+}  // namespace hit_test
+}  // namespace viz
+
+#endif  //  COMPONENTS_VIZ_HIT_TEST_HIT_TEST_AGGREGATOR_H_