Implement HitTestAggregator

components/viz/service/hit_test/hit_test_aggregator_unittest.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 "hit_test_aggregator.h"
+#include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/local_surface_id.h"
+#include "cc/surfaces/surface_id.h"
+#include "display_hit_test_data_factory_local.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace viz {
+namespace hit_test {
+namespace test {
+
+namespace {
+
+constexpr cc::FrameSinkId kDisplayFrameSink(2, 0);
+
+cc::SurfaceId MakeSurfaceId(const cc::FrameSinkId& frame_sink_id,
+                            uint32_t local_id) {
+  return cc::SurfaceId(
+      frame_sink_id,
+      cc::LocalSurfaceId(local_id, base::UnguessableToken::Deserialize(0, 1u)));
+}
+
+}  // namespace
+
+using namespace hit_test::mojom;
+
+class HitTestAggregatorTest : public testing::Test {
+ public:
+  HitTestAggregatorTest()
+      : aggregator_(
+            base::MakeUnique<hit_test::DisplayHitTestDataFactoryLocal>()) {}
+  ~HitTestAggregatorTest() override {}
+

[varkha, 2017/06/20 19:56:59]

nit: // testing::Test:

[gklassen, 2017/06/26 21:55:20]

Done.

+  void SetUp() override {}
+
+  void TearDown() override { Reset(); }
+
+  HitTestAggregator aggregator_;
+
+  int count() {
+    DisplayHitTestRegion* start = aggregator_.GetCurrentRegions();
+    DisplayHitTestRegion* end = start;
+    while (end->child_count != kEndOfList) {
+      end++;
+    }
+    int count = end - start;
+    return count;
+  }
+
+  DisplayHitTestRegion* RegionAtIndex(int i) {
+    return aggregator_.GetCurrentRegions() + i;
+  }
+
+  int GetPendingCount() { return aggregator_.pending_.size(); }
+  int GetActiveCount() { return aggregator_.active_.size(); }
+
+  int GetPendingRegionCount() { return RegionCount(aggregator_.pending_); }
+  int GetActiveRegionCount() { return RegionCount(aggregator_.active_); }
+
+  void CallOnSurfaceWillDraw(cc::SurfaceId surface_id) {
+    aggregator_.OnSurfaceWillDraw(surface_id);
+  }
+
+  int RegionCount(const HitTestDataMap& map) {
+    int size = 0;
+    for (auto const& it : map) {
+      hit_test::mojom::HitTestData* hit_test_data = it.second.get();
+      size += hit_test_data->regions.size();
+    }
+    return size;
+  }
+
+  void Reset() {
+    int size = aggregator_.display_hit_test_data_->length;
+
+    aggregator_.display_hit_test_data_->regions[0].child_count = kEndOfList;
+    aggregator_.display_hit_test_data_->regions[size >> 1].child_count =
+        kEndOfList;
+
+    aggregator_.pending_.clear();
+    aggregator_.active_.clear();
+  }
+
+  int GetDisplayHitTestDataLength() {
+    return aggregator_.display_hit_test_data_->length;
+  }
+
+  // Creates a hit test data element with 8 children recursively to
+  // the specified depth.  SurfaceIds are generated in sequential order and
+  // the method returns the next unused id ( also matches the count ).
+  int CreateAndSubmitHitTestDataWith8Children(int id, int depth) {
+    cc::SurfaceId surface_id = MakeSurfaceId(kDisplayFrameSink, id);
+    id++;
+
+    auto hit_test_data = HitTestData::New();
+    hit_test_data->surface_id = surface_id;
+    hit_test_data->flags = kHitTestMine;
+    hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+    for (int i = 0; i < 8; i++) {
+      auto hit_test_region = HitTestRegion::New();
+      hit_test_region->rect.SetRect(100, 100, 100, 100);
+
+      if (depth > 0) {
+        hit_test_region->flags = kHitTestChildSurface;
+        hit_test_region->surface_id = MakeSurfaceId(kDisplayFrameSink, id);
+        id = CreateAndSubmitHitTestDataWith8Children(id, depth - 1);
+      } else {
+        hit_test_region->flags = kHitTestMine;
+      }
+      hit_test_data->regions.push_back(std::move(hit_test_region));
+    }
+
+    aggregator_.SubmitHitTestData(std::move(hit_test_data));
+    return id;
+  }
+};
+
+// TODO(gklassen): Add tests for 3D use cases as suggested by and with
+// input from rjkroege.
+
+// One surface.
+//
+//  +----------+
+//  |          |
+//  |          |
+//  |          |
+//  +----------+
+//
+TEST_F(HitTestAggregatorTest, OneSurface) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId display_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+
+  auto hit_test_data = HitTestData::New();
+  hit_test_data->surface_id = display_surface_id;
+  hit_test_data->flags = kHitTestMine;
+  hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  aggregator_.SubmitHitTestData(std::move(hit_test_data));
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_EQ(GetPendingCount(), 1);
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(display_surface_id);
+
+  EXPECT_EQ(GetPendingCount(), 0);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  aggregator_.Aggregate(display_surface_id);
+  aggregator_.Swap();
+
+  // Expect 1 entry routing all events to the one surface ( display root ).
+  EXPECT_EQ(count(), 1);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, display_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 0);
+}
+
+// One opaque embedder with two regions.
+//
+//  +e-------------+
+//  | +r1-+ +r2--+ |
+//  | |   | |    | |
+//  | |   | |    | |
+//  | +---+ +----+ |
+//  +--------------+
+//
+TEST_F(HitTestAggregatorTest, OneEmbedderTwoRegions) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId e_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+
+  auto e_hit_test_data = HitTestData::New();
+  e_hit_test_data->surface_id = e_surface_id;
+  e_hit_test_data->flags = kHitTestMine;
+  e_hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  auto e_hit_test_region_r1 = HitTestRegion::New();
+  e_hit_test_region_r1->flags = kHitTestMine;
+  e_hit_test_region_r1->rect.SetRect(100, 100, 200, 400);
+
+  auto e_hit_test_region_r2 = HitTestRegion::New();
+  e_hit_test_region_r2->flags = kHitTestMine;
+  e_hit_test_region_r2->rect.SetRect(400, 100, 300, 400);
+
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_r1));
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_r2));
+
+  // Submit HitTestData.
+
+  EXPECT_EQ(GetPendingCount(), 0);
+
+  aggregator_.SubmitHitTestData(std::move(e_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 1);
+
+  // Add Surfaces to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(e_surface_id);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(e_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+  EXPECT_EQ(count(), 3);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 2);
+
+  region = RegionAtIndex(1);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 200, 400));
+  EXPECT_EQ(region->child_count, 0);
+
+  region = RegionAtIndex(2);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->rect, gfx::Rect(400, 100, 300, 400));
+  EXPECT_EQ(region->child_count, 0);
+}
+
+// One embedder with two children.
+//
+//  +e-------------+
+//  | +c1-+ +c2--+ |
+//  | |   | |    | |
+//  | |   | |    | |
+//  | +---+ +----+ |
+//  +--------------+
+//
+
+TEST_F(HitTestAggregatorTest, OneEmbedderTwoChildren) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId e_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+  cc::SurfaceId c1_surface_id = MakeSurfaceId(kDisplayFrameSink, 2);
+  cc::SurfaceId c2_surface_id = MakeSurfaceId(kDisplayFrameSink, 3);
+
+  auto e_hit_test_data = HitTestData::New();
+  e_hit_test_data->surface_id = e_surface_id;
+  e_hit_test_data->flags = kHitTestMine;
+  e_hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  auto e_hit_test_region_c1 = HitTestRegion::New();
+  e_hit_test_region_c1->flags = kHitTestChildSurface;
+  e_hit_test_region_c1->surface_id = c1_surface_id;
+  e_hit_test_region_c1->rect.SetRect(100, 100, 200, 300);
+
+  auto e_hit_test_region_c2 = HitTestRegion::New();
+  e_hit_test_region_c2->flags = kHitTestChildSurface;
+  e_hit_test_region_c2->surface_id = c2_surface_id;
+  e_hit_test_region_c2->rect.SetRect(400, 100, 400, 300);
+
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_c1));
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_c2));
+
+  auto c1_hit_test_data = HitTestData::New();
+  c1_hit_test_data->surface_id = c1_surface_id;
+
+  auto c2_hit_test_data = HitTestData::New();
+  c2_hit_test_data->surface_id = c2_surface_id;
+
+  // Submit ( in unexpected order ).
+
+  EXPECT_EQ(GetPendingCount(), 0);
+
+  aggregator_.SubmitHitTestData(std::move(c1_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 1);
+
+  aggregator_.SubmitHitTestData(std::move(e_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 2);
+
+  aggregator_.SubmitHitTestData(std::move(c2_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 3);
+
+  // Surfaces added to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(c2_surface_id);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  CallOnSurfaceWillDraw(c1_surface_id);
+  EXPECT_EQ(GetActiveCount(), 2);
+
+  CallOnSurfaceWillDraw(e_surface_id);
+  EXPECT_EQ(GetActiveCount(), 3);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(e_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+
+  EXPECT_EQ(count(), 3);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 2);
+
+  region = RegionAtIndex(1);
+  EXPECT_EQ(region->flags, kHitTestChildSurface);
+  EXPECT_EQ(region->frame_sink_id, c1_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 200, 300));
+  EXPECT_EQ(region->child_count, 0);
+
+  region = RegionAtIndex(2);
+  EXPECT_EQ(region->flags, kHitTestChildSurface);

[riajiang, 2017/06/20 23:54:59]

Was thinking to make sure that I understand this test case: so the difference
between this one and OneEmbedderTwoRegions is whether they are regions or
children? Does that mean in this case c1 and c2 can't receive events (i.e. all
events should go to e) since they both only have kHitTestChildSurface flag but
not kHitTestMine (as opposed to kHitTestChildSurface | kHitTestMine in
OccludedChildFrame for c)?

[gklassen, 2017/06/26 21:55:20]

Yes.

+  EXPECT_EQ(region->frame_sink_id, c2_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(400, 100, 400, 300));
+  EXPECT_EQ(region->child_count, 0);
+}
+
+// Occluded child frame ( OOPIF ).
+//
+//  +e-----------+
+//  | +c--+      |
+//  | | +div-+   |
+//  | | |    |   |
+//  | | +----+   |
+//  | +---+      |
+//  +------------+
+//
+
+TEST_F(HitTestAggregatorTest, OccludedChildFrame) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId e_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+  cc::SurfaceId c_surface_id = MakeSurfaceId(kDisplayFrameSink, 2);
+
+  auto e_hit_test_data = HitTestData::New();
+  e_hit_test_data->surface_id = e_surface_id;
+  e_hit_test_data->flags = kHitTestMine;
+  e_hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  auto e_hit_test_region_div = HitTestRegion::New();
+  e_hit_test_region_div->flags = kHitTestMine;
+  e_hit_test_region_div->surface_id = e_surface_id;
+  e_hit_test_region_div->rect.SetRect(200, 200, 300, 200);
+
+  auto e_hit_test_region_c = HitTestRegion::New();
+  e_hit_test_region_c->flags = kHitTestChildSurface;
+  e_hit_test_region_c->surface_id = c_surface_id;
+  e_hit_test_region_c->rect.SetRect(100, 100, 200, 500);
+
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_div));
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_c));
+
+  auto c_hit_test_data = HitTestData::New();
+  c_hit_test_data->surface_id = c_surface_id;
+  c_hit_test_data->flags = kHitTestMine;
+  c_hit_test_data->bounds.SetRect(0, 0, 200, 500);
+
+  // Submit ( in unexpected order ).
+
+  EXPECT_EQ(GetPendingCount(), 0);
+
+  aggregator_.SubmitHitTestData(std::move(c_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 1);
+
+  aggregator_.SubmitHitTestData(std::move(e_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 2);
+
+  // Surfaces added to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(e_surface_id);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  CallOnSurfaceWillDraw(c_surface_id);
+  EXPECT_EQ(GetActiveCount(), 2);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(e_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+
+  EXPECT_EQ(count(), 3);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 2);
+
+  region = RegionAtIndex(1);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(200, 200, 300, 200));
+  EXPECT_EQ(region->child_count, 0);
+
+  region = RegionAtIndex(2);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, c_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 200, 500));
+  EXPECT_EQ(region->child_count, 0);
+}
+
+// One embedder with a clipped child with a tab and transparent background.
+//
+//  +e-------------+
+//  |   +c---------|     Point   maps to
+//  | 1 |+a--+     |     -----   -------
+//  |   || 2 |  3  |       1        e
+//  |   |+b--------|       2        a
+//  |   ||         |       3        e ( transparent area in c )
+//  |   ||   4     |       4        b
+//  +--------------+
+//
+
+TEST_F(HitTestAggregatorTest, ClippedChildWithTabAndTransparentBackground) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId e_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+  cc::SurfaceId c_surface_id = MakeSurfaceId(kDisplayFrameSink, 2);
+  cc::SurfaceId a_surface_id = MakeSurfaceId(kDisplayFrameSink, 3);
+  cc::SurfaceId b_surface_id = MakeSurfaceId(kDisplayFrameSink, 4);
+
+  auto e_hit_test_data = HitTestData::New();
+  e_hit_test_data->surface_id = e_surface_id;
+  e_hit_test_data->flags = kHitTestMine;
+  e_hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  auto e_hit_test_region_c = HitTestRegion::New();
+  e_hit_test_region_c->flags = kHitTestChildSurface;
+  e_hit_test_region_c->surface_id = c_surface_id;
+  e_hit_test_region_c->rect.SetRect(200, 100, 1600, 800);
+  e_hit_test_region_c->transform.Translate(200, 100);
+
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_c));
+
+  auto c_hit_test_data = HitTestData::New();
+  c_hit_test_data->surface_id = c_surface_id;
+  c_hit_test_data->flags = kHitTestIgnore;
+  c_hit_test_data->bounds.SetRect(0, 0, 1600, 800);
+
+  auto c_hit_test_region_a = HitTestRegion::New();
+  c_hit_test_region_a->flags = kHitTestChildSurface;
+  c_hit_test_region_a->surface_id = a_surface_id;
+  c_hit_test_region_a->rect.SetRect(0, 0, 200, 100);
+
+  auto c_hit_test_region_b = HitTestRegion::New();
+  c_hit_test_region_b->flags = kHitTestChildSurface;
+  c_hit_test_region_b->surface_id = b_surface_id;
+  c_hit_test_region_b->rect.SetRect(0, 100, 800, 600);
+
+  c_hit_test_data->regions.push_back(std::move(c_hit_test_region_a));
+  c_hit_test_data->regions.push_back(std::move(c_hit_test_region_b));
+
+  auto a_hit_test_data = HitTestData::New();
+  a_hit_test_data->surface_id = a_surface_id;
+  a_hit_test_data->flags = kHitTestMine;
+  a_hit_test_data->bounds.SetRect(0, 0, 200, 100);
+
+  auto b_hit_test_data = HitTestData::New();
+  b_hit_test_data->surface_id = b_surface_id;
+  b_hit_test_data->flags = kHitTestMine;
+  b_hit_test_data->bounds.SetRect(0, 100, 800, 600);
+
+  // Submit ( in unexpected order ).
+
+  EXPECT_EQ(GetPendingCount(), 0);
+
+  aggregator_.SubmitHitTestData(std::move(c_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 1);
+
+  aggregator_.SubmitHitTestData(std::move(a_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 2);
+
+  aggregator_.SubmitHitTestData(std::move(b_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 3);
+
+  aggregator_.SubmitHitTestData(std::move(e_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 4);
+
+  // Surfaces added to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(c_surface_id);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  CallOnSurfaceWillDraw(e_surface_id);
+  EXPECT_EQ(GetActiveCount(), 2);
+
+  CallOnSurfaceWillDraw(b_surface_id);
+  EXPECT_EQ(GetActiveCount(), 3);
+
+  CallOnSurfaceWillDraw(a_surface_id);
+  EXPECT_EQ(GetActiveCount(), 4);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(e_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+
+  EXPECT_EQ(count(), 4);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 3);
+
+  region = RegionAtIndex(1);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestIgnore);
+  EXPECT_EQ(region->frame_sink_id, c_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(200, 100, 1600, 800));
+  EXPECT_EQ(region->child_count, 2);
+
+  gfx::Point point(300, 300);
+  region->transform.TransformPointReverse(&point);
+  EXPECT_TRUE(point == gfx::Point(100, 200));
+
+  region = RegionAtIndex(2);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, a_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 200, 100));
+  EXPECT_EQ(region->child_count, 0);
+
+  region = RegionAtIndex(3);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, b_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 100, 800, 600));
+  EXPECT_EQ(region->child_count, 0);
+}
+
+// Three children deep.
+//
+//  +e------------+
+//  | +c1-------+ |
+//  | | +c2---+ | |
+//  | | | +c3-| | |
+//  | | | |   | | |
+//  | | | +---| | |
+//  | | +-----+ | |
+//  | +---------+ |
+//  +-------------+
+//
+
+TEST_F(HitTestAggregatorTest, ThreeChildrenDeep) {
+  EXPECT_EQ(count(), 0);
+
+  cc::SurfaceId e_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+  cc::SurfaceId c1_surface_id = MakeSurfaceId(kDisplayFrameSink, 2);
+  cc::SurfaceId c2_surface_id = MakeSurfaceId(kDisplayFrameSink, 3);
+  cc::SurfaceId c3_surface_id = MakeSurfaceId(kDisplayFrameSink, 4);
+
+  auto e_hit_test_data = HitTestData::New();
+  e_hit_test_data->surface_id = e_surface_id;
+  e_hit_test_data->flags = kHitTestMine;
+  e_hit_test_data->bounds.SetRect(0, 0, 1024, 768);
+
+  auto e_hit_test_region_c1 = HitTestRegion::New();
+  e_hit_test_region_c1->flags = kHitTestChildSurface;
+  e_hit_test_region_c1->surface_id = c1_surface_id;
+  e_hit_test_region_c1->rect.SetRect(100, 100, 700, 700);
+
+  e_hit_test_data->regions.push_back(std::move(e_hit_test_region_c1));
+
+  auto c1_hit_test_data = HitTestData::New();
+  c1_hit_test_data->surface_id = c1_surface_id;
+  c1_hit_test_data->flags = kHitTestMine;
+  c1_hit_test_data->bounds.SetRect(0, 0, 600, 600);
+
+  auto c1_hit_test_region_c2 = HitTestRegion::New();
+  c1_hit_test_region_c2->flags = kHitTestChildSurface;
+  c1_hit_test_region_c2->surface_id = c2_surface_id;
+  c1_hit_test_region_c2->rect.SetRect(100, 100, 500, 500);
+
+  c1_hit_test_data->regions.push_back(std::move(c1_hit_test_region_c2));
+
+  auto c2_hit_test_data = HitTestData::New();
+  c2_hit_test_data->surface_id = c2_surface_id;
+  c2_hit_test_data->flags = kHitTestMine;
+  c2_hit_test_data->bounds.SetRect(0, 0, 400, 400);
+
+  auto c2_hit_test_region_c3 = HitTestRegion::New();
+  c2_hit_test_region_c3->flags = kHitTestChildSurface;
+  c2_hit_test_region_c3->surface_id = c3_surface_id;
+  c2_hit_test_region_c3->rect.SetRect(100, 100, 300, 300);
+
+  c2_hit_test_data->regions.push_back(std::move(c2_hit_test_region_c3));
+
+  auto c3_hit_test_data = HitTestData::New();
+  c3_hit_test_data->surface_id = c3_surface_id;
+  c3_hit_test_data->flags = kHitTestMine;
+  c3_hit_test_data->bounds.SetRect(0, 0, 200, 200);
+
+  // Submit ( in unexpected order ).
+
+  EXPECT_EQ(GetPendingCount(), 0);
+
+  aggregator_.SubmitHitTestData(std::move(c1_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 1);
+
+  aggregator_.SubmitHitTestData(std::move(c3_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 2);
+
+  aggregator_.SubmitHitTestData(std::move(e_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 3);
+
+  aggregator_.SubmitHitTestData(std::move(c2_hit_test_data));
+  EXPECT_EQ(GetPendingCount(), 4);
+
+  // Surfaces added to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  CallOnSurfaceWillDraw(c2_surface_id);
+  EXPECT_EQ(GetActiveCount(), 1);
+
+  CallOnSurfaceWillDraw(c1_surface_id);
+  EXPECT_EQ(GetActiveCount(), 2);
+
+  CallOnSurfaceWillDraw(e_surface_id);
+  EXPECT_EQ(GetActiveCount(), 3);
+
+  CallOnSurfaceWillDraw(c3_surface_id);
+  EXPECT_EQ(GetActiveCount(), 4);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(e_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+
+  EXPECT_EQ(count(), 4);
+
+  DisplayHitTestRegion* region;
+
+  region = RegionAtIndex(0);
+  EXPECT_EQ(region->flags, kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, e_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(0, 0, 1024, 768));
+  EXPECT_EQ(region->child_count, 3);
+
+  region = RegionAtIndex(1);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, c1_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 700, 700));
+  EXPECT_EQ(region->child_count, 2);
+
+  region = RegionAtIndex(2);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, c2_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 500, 500));
+  EXPECT_EQ(region->child_count, 1);
+
+  region = RegionAtIndex(3);
+  EXPECT_EQ(region->flags, kHitTestChildSurface | kHitTestMine);
+  EXPECT_EQ(region->frame_sink_id, c3_surface_id.frame_sink_id());
+  EXPECT_EQ(region->rect, gfx::Rect(100, 100, 300, 300));
+  EXPECT_EQ(region->child_count, 0);

[riajiang, 2017/06/20 23:54:59]

Can we maybe add a test case where e has two children, c1 and d where d is under
c1 to confirm which z-order (back-to-front or front-to-back) we are using?

[gklassen, 2017/06/26 21:55:20]

Good call, thank you.  Test Added. Done.

+}
+
+// Exceed limits to ensure that bounds and resize work.
+//
+// A tree of embedders each with 8 children and 4 levels deep = 4096 regions.
+// This will exceed initial allocation and force a resize.
+//
+//  +e--------------------------------------------------------+
+//  | +c1----------++c2----------++c3----------++c4----------+|
+//  | | +c1--------|| +c1--------|| +c1--------|| +c1--------||
+//  | | | +c1-++c2-|| | +c1-++c2-|| | +c1-++c2-|| | +c1-++c2-||
+//  | | | |   ||   || | |   ||   || | |   ||   || | |   ||   ||
+//  | | | +---++---|| | +---++---|| | +---++---|| | +---++---||
+//  | +------------++------------++------------++------------+|
+//  | +c5----------++c6----------++c7----------++c8----------+|
+//  | | +c1--------|| +c1--------|| +c1--------|| +c1--------||
+//  | | | +c1-++c2-|| | +c1-++c2-|| | +c1-++c2-|| | +c1-++c2-||
+//  | | | |   ||   || | |   ||   || | |   ||   || | |   ||   ||
+//  | | | +---++---|| | +---++---|| | +---++---|| | +---++---||
+//  | +------------++------------++------------++------------+|
+//  +---------------------------------------------------------+
+//
+
+TEST_F(HitTestAggregatorTest, ExceedLimits) {
+  EXPECT_EQ(count(), 0);
+
+  EXPECT_LT(GetDisplayHitTestDataLength(), 4096);
+
+  cc::SurfaceId display_surface_id = MakeSurfaceId(kDisplayFrameSink, 1);
+
+  int next_surface_id = CreateAndSubmitHitTestDataWith8Children(1, 3);
+  int surface_count = next_surface_id - 1;
+
+  int region_count = GetPendingRegionCount();
+
+  // Expect 4680 regions:
+  //  8 children 4 levels deep 8*8*8*8 is  4096
+  //  1 region for each embedder/surface +  584
+  //                                      -----
+  //                                       4680.
+  EXPECT_EQ(region_count, 4680);
+
+  EXPECT_EQ(GetPendingCount(), surface_count);
+
+  // Mark Surfaces as added to DisplayFrame ( in unexpected order ).
+
+  EXPECT_EQ(count(), 0);
+  EXPECT_EQ(GetActiveCount(), 0);
+
+  for (int i = 1; i <= surface_count; i++) {
+    cc::SurfaceId surface_id = MakeSurfaceId(kDisplayFrameSink, i);
+    CallOnSurfaceWillDraw(surface_id);
+  }
+
+  EXPECT_EQ(GetActiveCount(), surface_count);
+
+  // Aggregate and swap.
+
+  aggregator_.Aggregate(display_surface_id);
+  EXPECT_EQ(count(), 0);
+
+  aggregator_.Swap();
+
+  EXPECT_EQ(count(), region_count + 1);
+
+  EXPECT_GE(GetDisplayHitTestDataLength(), region_count);
+}
+
+}  // namespace test
+}  // namespace hit_test
+}  // namespace viz