Add temporary reference ownership to SurfaceManager.

cc/surfaces/surface_manager_ref_unittest.cc

 // Copyright 2016 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 <stddef.h>
 
 #include <unordered_map>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
@@ skipping 53 matching lines @@
       factory_ptr = base::MakeUnique<SurfaceFactory>(frame_sink_id,
                                                      manager_.get(), &client_);
     return *factory_ptr;
   }
 
   void RemoveSurfaceReference(const SurfaceId& parent_id,
                               const SurfaceId& child_id) {
     manager_->RemoveSurfaceReferences({SurfaceReference(parent_id, child_id)});
   }
 
+  void AddSurfaceReference(const SurfaceId& parent_id,
+                           const SurfaceId& child_id) {
+    manager_->AddSurfaceReferences({SurfaceReference(parent_id, child_id)});
+  }
+
   // Returns all the references where |surface_id| is the parent.
   const SurfaceManager::SurfaceIdSet& GetReferencesFrom(
       const SurfaceId& surface_id) {
     return manager().parent_to_child_refs_[surface_id];
   }
 
   // Returns all the references where |surface_id| is the child.
   const SurfaceManager::SurfaceIdSet& GetReferencesFor(
       const SurfaceId& surface_id) {
     return manager().child_to_parent_refs_[surface_id];
   }
 
-  const SurfaceManager::SurfaceIdSet& GetReferencesFromRoot() {
-    return GetReferencesFrom(manager().GetRootSurfaceId());
-  }
-
-  // Returns all the temporary references for the given frame sink id.
-  std::vector<LocalSurfaceId> GetTempReferencesFor(
-      const FrameSinkId& frame_sink_id) {
-    return manager().temp_references_[frame_sink_id];
-  }
-
   // Temporary references are stored as a map in SurfaceManager. This method
   // converts the map to a vector.
   std::vector<SurfaceId> GetAllTempReferences() {
     std::vector<SurfaceId> temp_references;
-    for (auto& map_entry : manager().temp_references_) {
-      for (auto local_surface_id : map_entry.second)
-        temp_references.push_back(SurfaceId(map_entry.first, local_surface_id));
-    }
+    for (auto& map_entry : manager().temporary_references_)
+      temp_references.push_back(map_entry.first);
     return temp_references;
   }
 
  protected:
   // testing::Test:
   void SetUp() override {
     // Start each test with a fresh SurfaceManager instance.
     manager_ = base::MakeUnique<SurfaceManager>(
         SurfaceManager::LifetimeType::REFERENCES);
   }
   void TearDown() override {
     for (auto& factory : factories_)
       factory.second->EvictSurface();
     factories_.clear();
     manager_.reset();
   }
 
   std::unordered_map<FrameSinkId,
                      std::unique_ptr<SurfaceFactory>,
                      FrameSinkIdHash>
       factories_;
   std::unique_ptr<SurfaceManager> manager_;
   StubSurfaceFactoryClient client_;
 };
 
 TEST_F(SurfaceManagerRefTest, AddReference) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
 
   EXPECT_THAT(GetReferencesFor(id1),
               UnorderedElementsAre(manager().GetRootSurfaceId()));
   EXPECT_THAT(GetReferencesFrom(id1), IsEmpty());
 }
 
 TEST_F(SurfaceManagerRefTest, AddRemoveReference) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
 
   EXPECT_THAT(GetReferencesFor(id1),
               UnorderedElementsAre(manager().GetRootSurfaceId()));
   EXPECT_THAT(GetReferencesFor(id2), UnorderedElementsAre(id1));
   EXPECT_THAT(GetReferencesFrom(id1), UnorderedElementsAre(id2));
   EXPECT_THAT(GetReferencesFrom(id2), IsEmpty());
 
   RemoveSurfaceReference(id1, id2);
   EXPECT_THAT(GetReferencesFor(id1), SizeIs(1));
   EXPECT_THAT(GetReferencesFor(id2), IsEmpty());
   EXPECT_THAT(GetReferencesFrom(id1), IsEmpty());
   EXPECT_THAT(GetReferencesFrom(id2), IsEmpty());
 }
 
 TEST_F(SurfaceManagerRefTest, NewSurfaceFromFrameSink) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
   SurfaceId id3 = CreateSurface(kFrameSink3, 1);
 
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
-  manager().AddSurfaceReference(id2, id3);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
+  AddSurfaceReference(id2, id3);
 
   // |kFramesink2| received a CompositorFrame with a new size, so it destroys
   // |id2| and creates |id2_next|. No reference have been removed yet.
   SurfaceId id2_next = CreateSurface(kFrameSink2, 2);
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2_next));
 
   // Add references to and from |id2_next|.
-  manager().AddSurfaceReference(id1, id2_next);
-  manager().AddSurfaceReference(id2_next, id3);
+  AddSurfaceReference(id1, id2_next);
+  AddSurfaceReference(id2_next, id3);
   EXPECT_THAT(GetReferencesFor(id2), UnorderedElementsAre(id1));
   EXPECT_THAT(GetReferencesFor(id2_next), UnorderedElementsAre(id1));
   EXPECT_THAT(GetReferencesFor(id3), UnorderedElementsAre(id2, id2_next));
 
   RemoveSurfaceReference(id1, id2);
   EXPECT_THAT(GetReferencesFor(id2), IsEmpty());
   EXPECT_THAT(GetReferencesFor(id2_next), UnorderedElementsAre(id1));
   EXPECT_THAT(GetReferencesFor(id3), UnorderedElementsAre(id2_next));
 
   // |id2| should be deleted during GC but other surfaces shouldn't.
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id2));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2_next));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id3));
 }
 
 TEST_F(SurfaceManagerRefTest, ReferenceCycleGetsDeleted) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
   SurfaceId id3 = CreateSurface(kFrameSink3, 1);
 
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
-  manager().AddSurfaceReference(id2, id3);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
+  AddSurfaceReference(id2, id3);
 
   // This reference forms a cycle between id2 and id3.
-  manager().AddSurfaceReference(id3, id2);
+  AddSurfaceReference(id3, id2);
 
   DestroySurface(id3);
   DestroySurface(id2);
   DestroySurface(id1);
 
   RemoveSurfaceReference(manager().GetRootSurfaceId(), id1);
 
   // Removing the reference from the root to id1 should allow all three surfaces
   // to be deleted during GC even with a cycle between 2 and 3.
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id1));
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id2));
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id3));
 }
 
 TEST_F(SurfaceManagerRefTest, CheckGC) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
 
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
 
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id1));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
 
   // Destroying the surfaces shouldn't delete them yet, since there is still an
   // active reference on all surfaces.
   DestroySurface(id1);
   DestroySurface(id2);
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id1));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
 
   // Should delete |id2| when the only reference to it is removed.
   RemoveSurfaceReference(id1, id2);
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id2));
 
   // Should delete |id1| when the only reference to it is removed.
   RemoveSurfaceReference(manager().GetRootSurfaceId(), id1);
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id1));
 }
 
 TEST_F(SurfaceManagerRefTest, CheckGCRecusiveFull) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
   SurfaceId id3 = CreateSurface(kFrameSink3, 1);
 
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
-  manager().AddSurfaceReference(id2, id3);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
+  AddSurfaceReference(id2, id3);
 
   DestroySurface(id3);
   DestroySurface(id2);
   DestroySurface(id1);
 
   // Destroying the surfaces shouldn't delete them yet, since there is still an
   // active reference on all surfaces.
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id3));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
   EXPECT_NE(nullptr, manager().GetSurfaceForId(id1));
 
   RemoveSurfaceReference(manager().GetRootSurfaceId(), id1);
 
   // Removing the reference from the root to id1 should allow all three surfaces
   // to be deleted during GC.
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id1));
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id2));
   EXPECT_EQ(nullptr, manager().GetSurfaceForId(id3));
 }
 
 TEST_F(SurfaceManagerRefTest, TryDoubleAddReference) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
 
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), id1);
-  manager().AddSurfaceReference(id1, id2);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+  AddSurfaceReference(id1, id2);
   EXPECT_THAT(GetReferencesFor(id2), SizeIs(1));
   EXPECT_THAT(GetReferencesFrom(id1), SizeIs(1));
 
   // The second request should be ignored without crashing.
-  manager().AddSurfaceReference(id1, id2);
+  AddSurfaceReference(id1, id2);
   EXPECT_THAT(GetReferencesFor(id2), SizeIs(1));
   EXPECT_THAT(GetReferencesFrom(id1), SizeIs(1));
 }
 
 TEST_F(SurfaceManagerRefTest, TryAddSelfReference) {
-  SurfaceId id1 = CreateSurface(kFrameSink1, 1);
+  SurfaceId id1 = CreateSurface(kFrameSink2, 1);
 
   // A temporary reference must exist to |id1|.
-  EXPECT_THAT(GetReferencesFor(id1), SizeIs(1));
+  EXPECT_THAT(GetAllTempReferences(), ElementsAre(id1));
+  EXPECT_THAT(GetReferencesFrom(id1), IsEmpty());
+  EXPECT_THAT(GetReferencesFor(id1), IsEmpty());
 
   // Try to add a self reference. This should fail.
-  manager().AddSurfaceReference(id1, id1);
+  AddSurfaceReference(id1, id1);
 
-  // Adding a self reference should be ignored without crashing.
+  // Adding a self reference should be ignored without crashing. The temporary
+  // reference to |id1| must still exist.
+  EXPECT_THAT(GetAllTempReferences(), ElementsAre(id1));
   EXPECT_THAT(GetReferencesFrom(id1), IsEmpty());
-
-  // The temporary reference to |id1| must still exist.
-  EXPECT_THAT(GetReferencesFor(id1), SizeIs(1));
+  EXPECT_THAT(GetReferencesFor(id1), IsEmpty());
 }
 
 TEST_F(SurfaceManagerRefTest, TryRemoveBadReference) {
   SurfaceId id1 = CreateSurface(kFrameSink1, 1);
   SurfaceId id2 = CreateSurface(kFrameSink2, 1);
 
   // Removing non-existent reference should be ignored.
-  manager().AddSurfaceReference(id1, id2);
+  AddSurfaceReference(id1, id2);
   RemoveSurfaceReference(id2, id1);
   EXPECT_THAT(GetReferencesFrom(id1), SizeIs(1));
   EXPECT_THAT(GetReferencesFor(id2), SizeIs(1));
 }
 
 TEST_F(SurfaceManagerRefTest, AddSurfaceThenReference) {
   // Create a new surface.
   const SurfaceId surface_id = CreateSurface(kFrameSink2, 1);
 
   // A temporary reference must be added to |surface_id|.
   EXPECT_THAT(GetAllTempReferences(), ElementsAre(surface_id));
-  EXPECT_THAT(GetReferencesFromRoot(), ElementsAre(surface_id));
 
   // Create |parent_id| and add a real reference from it to |surface_id|.
   const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
-  manager().AddSurfaceReference(parent_id, surface_id);
+  AddSurfaceReference(parent_id, surface_id);
 
   // The temporary reference to |surface_id| should be gone.
   // The only temporary reference should be to |parent_id|.
   // There must be a real reference from |parent_id| to |child_id|.
   EXPECT_THAT(GetAllTempReferences(), ElementsAre(parent_id));
-  EXPECT_THAT(GetReferencesFromRoot(), ElementsAre(parent_id));
   EXPECT_THAT(GetReferencesFrom(parent_id), ElementsAre(surface_id));
 }
 
 TEST_F(SurfaceManagerRefTest, AddSurfaceThenRootReference) {
   // Create a new surface.
   const SurfaceId surface_id = CreateSurface(kFrameSink1, 1);
 
   // Temporary reference should be added to |surface_id|.
   EXPECT_THAT(GetAllTempReferences(), ElementsAre(surface_id));
-  EXPECT_THAT(GetReferencesFromRoot(), ElementsAre(surface_id));
 
   // Add a real reference from root to |surface_id|.
-  manager().AddSurfaceReference(manager().GetRootSurfaceId(), surface_id);
+  AddSurfaceReference(manager().GetRootSurfaceId(), surface_id);
 
   // The temporary reference should be gone.
   // There should now be a real reference from root to |surface_id|.
   EXPECT_TRUE(GetAllTempReferences().empty());
-  EXPECT_THAT(GetReferencesFromRoot(), ElementsAre(surface_id));
+  EXPECT_THAT(GetReferencesFrom(manager().GetRootSurfaceId()),
+              ElementsAre(surface_id));
 }
 
 TEST_F(SurfaceManagerRefTest, AddTwoSurfacesThenOneReference) {
   // Create two surfaces with different FrameSinkIds.
   const SurfaceId surface_id1 = CreateSurface(kFrameSink2, 1);
   const SurfaceId surface_id2 = CreateSurface(kFrameSink3, 1);
 
   // Temporary reference should be added for both surfaces.
   EXPECT_THAT(GetAllTempReferences(),
               UnorderedElementsAre(surface_id1, surface_id2));
-  EXPECT_THAT(GetReferencesFromRoot(),
-              UnorderedElementsAre(surface_id1, surface_id2));
 
   // Create |parent_id| and add a real reference from it to |surface_id1|.
   const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
-  manager().AddSurfaceReference(parent_id, surface_id1);
+  AddSurfaceReference(parent_id, surface_id1);
 
   // Real reference must be added to |surface_id1| and the temporary reference
   // to it must be gone.
   // There should still be a temporary reference left to |surface_id2|.
   // A temporary reference to |parent_id| must be created.
   EXPECT_THAT(GetAllTempReferences(),
               UnorderedElementsAre(parent_id, surface_id2));
-  EXPECT_THAT(GetReferencesFromRoot(),
-              UnorderedElementsAre(parent_id, surface_id2));
   EXPECT_THAT(GetReferencesFrom(parent_id), ElementsAre(surface_id1));
 }
 
 TEST_F(SurfaceManagerRefTest, AddSurfacesSkipReference) {
   // Add two surfaces that have the same FrameSinkId. This would happen when a
   // client submits two CompositorFrames before parent submits a new
   // CompositorFrame.
   const SurfaceId surface_id1 = CreateSurface(kFrameSink2, 2);
   const SurfaceId surface_id2 = CreateSurface(kFrameSink2, 1);
 
   // Temporary references should be added for both surfaces and they should be
   // stored in the order of creation.
-  EXPECT_THAT(GetTempReferencesFor(surface_id1.frame_sink_id()),
-              ElementsAre(surface_id1.local_surface_id(),
-                          surface_id2.local_surface_id()));
-  EXPECT_THAT(GetReferencesFromRoot(),
+  EXPECT_THAT(GetAllTempReferences(),
               UnorderedElementsAre(surface_id1, surface_id2));
 
   // Create |parent_id| and add a reference from it to |surface_id2| which was
   // created later.
   const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
-  manager().AddSurfaceReference(parent_id, surface_id2);
+  AddSurfaceReference(parent_id, surface_id2);
 
   // The real reference should be added for |surface_id2| and the temporary
   // references to both |surface_id1| and |surface_id2| should be gone.
   // There should be a temporary reference to |parent_id|.
   EXPECT_THAT(GetAllTempReferences(), ElementsAre(parent_id));
-  EXPECT_THAT(GetReferencesFromRoot(), ElementsAre(parent_id));
   EXPECT_THAT(GetReferencesFrom(parent_id), ElementsAre(surface_id2));
 }
 
 TEST_F(SurfaceManagerRefTest, RemoveFirstTempRefOnly) {
   // Add two surfaces that have the same FrameSinkId. This would happen when a
   // client submits two CFs before parent submits a new CF.
   const SurfaceId surface_id1 = CreateSurface(kFrameSink2, 1);
   const SurfaceId surface_id2 = CreateSurface(kFrameSink2, 2);
 
   // Temporary references should be added for both surfaces and they should be
   // stored in the order of creation.
-  EXPECT_THAT(GetTempReferencesFor(surface_id1.frame_sink_id()),
-              ElementsAre(surface_id1.local_surface_id(),
-                          surface_id2.local_surface_id()));
-  EXPECT_THAT(GetReferencesFromRoot(),
+  EXPECT_THAT(GetAllTempReferences(),
               UnorderedElementsAre(surface_id1, surface_id2));
 
   // Create |parent_id| and add a reference from it to |surface_id1| which was
   // created earlier.
   const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
-  manager().AddSurfaceReference(parent_id, surface_id1);
+  AddSurfaceReference(parent_id, surface_id1);
 
   // The real reference should be added for |surface_id1| and its temporary
   // reference should be removed. The temporary reference for |surface_id2|
   // should remain. A temporary reference must be added for |parent_id|.
   EXPECT_THAT(GetAllTempReferences(),
               UnorderedElementsAre(parent_id, surface_id2));
-  EXPECT_THAT(GetReferencesFromRoot(),
-              UnorderedElementsAre(parent_id, surface_id2));
   EXPECT_THAT(GetReferencesFrom(parent_id), ElementsAre(surface_id1));
 }
 
+TEST_F(SurfaceManagerRefTest, TemporaryReferenceNotGarbageCollected) {

[Fady Samuel, 2017/02/24 19:08:11]

Top level comment about what the unit test is trying to verify.

[kylechar, 2017/02/24 19:28:01]

I changed the name to be more descriptive. PTAL in other CL.

+  const SurfaceId id1 = CreateSurface(kFrameSink1, 1);
+  AddSurfaceReference(manager().GetRootSurfaceId(), id1);
+
+  const SurfaceId id2 = CreateSurface(kFrameSink2, 1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id2));
+  EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
+
+  // Destroy both surfaces and remove the reference to |id1|.

[Fady Samuel, 2017/02/24 19:08:11]

Add comment about when garbage collection happens.

[kylechar, 2017/02/24 19:28:01]

Done in other CL.

+  DestroySurface(id1);
+  DestroySurface(id2);
+  RemoveSurfaceReference(manager().GetRootSurfaceId(), id1);
+
+  // Without any references |id1| is deleted. There is still a temporary

[Fady Samuel, 2017/02/24 19:08:11]

Move the "There is still a temporary reference to |id2| so it is not deleted" to
the next line?

[kylechar, 2017/02/24 19:28:01]

Done in other CL.

+  // reference to |id2| so it is not deleted.
+  EXPECT_EQ(nullptr, manager().GetSurfaceForId(id1));
+  EXPECT_NE(nullptr, manager().GetSurfaceForId(id2));
+}
+
+TEST_F(SurfaceManagerRefTest, AssignTempReference) {

[Fady Samuel, 2017/02/24 19:08:11]

Top level comment about what the unit test is trying to verify.

[kylechar, 2017/02/24 19:57:29]

Done.

+  // The newly created surface should have a temporary reference.
+  const SurfaceId id1 = CreateSurface(kFrameSink2, 1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1));
+
+  // It should still have a temporary reference after an owner is assigned.
+  manager().AssignTemporaryReference(id1, kFrameSink1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1));
+
+  // When |kFrameSink1| is invalidated the temporary reference will be removed.
+  manager().InvalidateFrameSinkId(kFrameSink1);
+  ASSERT_THAT(GetAllTempReferences(), IsEmpty());
+}
+
+TEST_F(SurfaceManagerRefTest, InvalidateHasNoEffectOnSurfaceReferences) {

[Fady Samuel, 2017/02/24 19:08:11]

Top level comment about what the unit test is trying to verify.

[kylechar, 2017/02/24 19:57:29]

Done.

+  const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
+  AddSurfaceReference(manager().GetRootSurfaceId(), parent_id);
+
+  const SurfaceId id1 = CreateSurface(kFrameSink2, 1);
+  manager().AssignTemporaryReference(id1, kFrameSink1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1));
+
+  // Adding a real surface reference will remove the temporary reference.
+  AddSurfaceReference(parent_id, id1);
+  ASSERT_THAT(GetAllTempReferences(), IsEmpty());
+  ASSERT_THAT(GetReferencesFor(id1), UnorderedElementsAre(parent_id));
+
+  // When |kFrameSink1| is invalidated it shouldn't change the surface
+  // references.
+  manager().InvalidateFrameSinkId(kFrameSink1);
+  ASSERT_THAT(GetReferencesFor(id1), UnorderedElementsAre(parent_id));
+}
+
+TEST_F(SurfaceManagerRefTest, DropTempReference) {

[Fady Samuel, 2017/02/24 19:08:11]

Top level comment about what the unit test is trying to verify.

[kylechar, 2017/02/24 19:57:29]

Done-ish.

+  const SurfaceId id1 = CreateSurface(kFrameSink1, 1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1));
+
+  // An example of why this could happen is the window server doesn't know the
+  // owner, maybe it has crashed and been cleanup already, and asks to drop the
+  // temporary reference.
+  manager().DropTemporaryReference(id1);
+  ASSERT_THAT(GetAllTempReferences(), IsEmpty());
+}
+
+TEST_F(SurfaceManagerRefTest, DropOnlyOneTempReference) {

[Fady Samuel, 2017/02/24 19:08:11]

Top level comment about what the unit test is trying to verify.

[kylechar, 2017/02/24 19:57:29]

Done.

+  const SurfaceId parent_id = CreateSurface(kFrameSink1, 1);
+  AddSurfaceReference(manager().GetRootSurfaceId(), parent_id);
+
+  const SurfaceId id1a = CreateSurface(kFrameSink2, 1);
+  const SurfaceId id1b = CreateSurface(kFrameSink2, 2);
+
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1a, id1b));
+
+  // Assign |id1a| to |kFrameSink1|. This doesn't change the temporary
+  // reference, it just assigns as owner to it.
+  manager().AssignTemporaryReference(id1a, kFrameSink1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1a, id1b));
+
+  // When the owner is invalidated the temporary reference to |id2a| will
+  // removed.
+  manager().InvalidateFrameSinkId(kFrameSink1);
+  ASSERT_THAT(GetAllTempReferences(), UnorderedElementsAre(id1b));
+
+  // If the owner is invalidated then the Window Server might not

[Fady Samuel, 2017/02/24 19:08:11]

Incomplete sentence?

[kylechar, 2017/02/24 19:57:29]

Done.

+  manager().DropTemporaryReference(id1b);
+  ASSERT_THAT(GetAllTempReferences(), IsEmpty());
+}
+
 }  // namespace cc