Unit test to mirror actual behavior

The ParentLocalSurfaceIdAllocator unit tests have a function to get a
fake child-allocated LocalSurfaceId. It hard-codes values.

The hard-coded parent sequence number is bad but not terrible. It forces
knowledge of the calling functions. This isn't good. It can be improved.

However, the embed token part is pretty bad. It forces the unit tests to
assert the wrong behavior. A child allocation should use the parent's
embed token. Since the hard-coded value is different, the calling tests
assert that the embed tokens don't match when in reality they should.

To fix these bad behaviors, the fake child allocation should take a
parent allocator (or parent-allocated LocalSurfaceId) so the values can
be based on what the test provides.

BUG=837030

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: Iaa8e7b6226c0a6c6d67fa420183f24a36e7499ce
Reviewed-on: https://chromium-review.googlesource.com/1036530Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: Chris Blume <cblume@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554928}

components/viz/common/surfaces/parent_local_surface_id_allocator_unittest.cc

@@ -24,7 +24,8 @@ namespace {
     const LocalSurfaceId& local_surface_id);
 ::testing::AssertionResult NonceIsEmpty(const LocalSurfaceId& local_surface_id);
 
-LocalSurfaceId GetFakeChildAllocatedLocalSurfaceId();
+LocalSurfaceId GetFakeChildAllocatedLocalSurfaceId(
+    const ParentLocalSurfaceIdAllocator& parent_allocator);
 ParentLocalSurfaceIdAllocator GetChildUpdatedAllocator();
 
 }  // namespace
@@ -86,14 +87,14 @@ TEST(ParentLocalSurfaceIdAllocatorTest,
      UpdateFromChildOnlyUpdatesExpectedLocalSurfaceIdComponents) {
   ParentLocalSurfaceIdAllocator child_updated_parent_allocator;
   LocalSurfaceId preupdate_local_surface_id =
-      child_updated_parent_allocator.GetCurrentLocalSurfaceId();
+      child_updated_parent_allocator.GenerateId();
   LocalSurfaceId child_allocated_local_surface_id =
-      GetFakeChildAllocatedLocalSurfaceId();
-  EXPECT_NE(preupdate_local_surface_id.parent_sequence_number(),
+      GetFakeChildAllocatedLocalSurfaceId(child_updated_parent_allocator);
+  EXPECT_EQ(preupdate_local_surface_id.parent_sequence_number(),
             child_allocated_local_surface_id.parent_sequence_number());
   EXPECT_NE(preupdate_local_surface_id.child_sequence_number(),
             child_allocated_local_surface_id.child_sequence_number());
-  EXPECT_NE(preupdate_local_surface_id.embed_token(),
+  EXPECT_EQ(preupdate_local_surface_id.embed_token(),
             child_allocated_local_surface_id.embed_token());
 
   const LocalSurfaceId& returned_local_surface_id =
@@ -102,11 +103,11 @@ TEST(ParentLocalSurfaceIdAllocatorTest,
 
   const LocalSurfaceId& postupdate_local_surface_id =
       child_updated_parent_allocator.GetCurrentLocalSurfaceId();
-  EXPECT_NE(postupdate_local_surface_id.parent_sequence_number(),
+  EXPECT_EQ(postupdate_local_surface_id.parent_sequence_number(),
             child_allocated_local_surface_id.parent_sequence_number());
   EXPECT_EQ(postupdate_local_surface_id.child_sequence_number(),
             child_allocated_local_surface_id.child_sequence_number());
-  EXPECT_NE(postupdate_local_surface_id.embed_token(),
+  EXPECT_EQ(postupdate_local_surface_id.embed_token(),
             child_allocated_local_surface_id.embed_token());
   EXPECT_EQ(returned_local_surface_id,
             child_updated_parent_allocator.GetCurrentLocalSurfaceId());
@@ -193,19 +194,20 @@ namespace {
   return ::testing::AssertionFailure() << "embed_token() is not empty";
 }
 
-LocalSurfaceId GetFakeChildAllocatedLocalSurfaceId() {
-  constexpr uint32_t kParentSequenceNumber = 1;
-  constexpr uint32_t kChildSequenceNumber = 3;
-  const base::UnguessableToken embed_token = base::UnguessableToken::Create();
+LocalSurfaceId GetFakeChildAllocatedLocalSurfaceId(
+    const ParentLocalSurfaceIdAllocator& parent_allocator) {
+  const LocalSurfaceId& current_local_surface_id =
+      parent_allocator.GetCurrentLocalSurfaceId();
 
-  return LocalSurfaceId(kParentSequenceNumber, kChildSequenceNumber,
-                        embed_token);
+  return LocalSurfaceId(current_local_surface_id.parent_sequence_number(),
+                        current_local_surface_id.child_sequence_number() + 1,
+                        current_local_surface_id.embed_token());
 }
 
 ParentLocalSurfaceIdAllocator GetChildUpdatedAllocator() {
   ParentLocalSurfaceIdAllocator child_updated_parent_allocator;
   LocalSurfaceId child_allocated_local_surface_id =
-      GetFakeChildAllocatedLocalSurfaceId();
+      GetFakeChildAllocatedLocalSurfaceId(child_updated_parent_allocator);
   child_updated_parent_allocator.UpdateFromChild(
       child_allocated_local_surface_id);
   return child_updated_parent_allocator;