Rip out tag test for direct-map

Tags aren't implemented for direct-map, hence remove the unit test
entirely.

Technically, we should also prevent allocate size from being increased
by kInSlotTagBufferSize on that path, but that's too much effort.

Bug: 1092288
Change-Id: Iecffe61120bd4f9c0e9321040338eda44b3dbc66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2306121
Commit-Queue: Bartek Nowierski <bartekn@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#789891}

base/allocator/partition_allocator/partition_alloc_unittest.cc

@@ -2565,43 +2565,6 @@ TEST_F(PartitionAllocTest, TagBasic) {
 
 #endif
 
-#if ENABLE_TAG_FOR_CHECKED_PTR2
-
-TEST_F(PartitionAllocTest, TagForDirectMap) {
-  size_t request_size = kGenericMinDirectMappedDownsize + kExtraAllocSize;
-  void* ptr1 = allocator.root()->Alloc(request_size, type_name);
-  void* ptr2 = allocator.root()->Alloc(request_size, type_name);
-  EXPECT_TRUE(ptr1);
-  EXPECT_TRUE(ptr2);
-
-  PartitionRoot<ThreadSafe>::Page* page =
-      PartitionRoot<ThreadSafe>::Page::FromPointer(
-          PartitionPointerAdjustSubtract(true, ptr1));
-  EXPECT_TRUE(page);
-
-  constexpr PartitionTag kTag1 = 0xBADA;
-  constexpr PartitionTag kTag2 = 0xDB8A;
-  constexpr size_t unused_size = 0;
-  PartitionTagSetValue(ptr1, unused_size, kTag1);
-  PartitionTagSetValue(ptr2, unused_size, kTag2);
-
-  memset(ptr1, 0, request_size);
-  memset(ptr2, 0, request_size);
-  EXPECT_EQ(kTag1, PartitionTagGetValue(ptr1));
-  EXPECT_EQ(kTag2, PartitionTagGetValue(ptr2));
-
-  EXPECT_TRUE(!memchr(ptr1, static_cast<uint8_t>(kTag1 >> 8), kTestAllocSize));
-  EXPECT_TRUE(!memchr(ptr1, static_cast<uint8_t>(kTag1), kTestAllocSize));
-  EXPECT_TRUE(!memchr(ptr2, static_cast<uint8_t>(kTag2 >> 8), kTestAllocSize));
-  EXPECT_TRUE(!memchr(ptr2, static_cast<uint8_t>(kTag2), kTestAllocSize));
-
-  allocator.root()->Free(ptr1);
-  EXPECT_EQ(kTag2, PartitionTagGetValue(ptr2));
-  allocator.root()->Free(ptr2);
-}
-
-#endif
-
 }  // namespace internal
 }  // namespace base