[PA] Namespace migration (27 of N)

This CL migrates *Scan's `StateBitmap` into the `partition_alloc`
namespace. This affords us a small tweak in `partition_page`, where a
previous use of (::base::internal::)StateBitmap can be unqualified.

Bug: 1288247
Change-Id: I7ba5320582877fabfdb1b09e0b3902b5d9dc8071
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3557870
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Kalvin Lee <kdlee@chromium.org>
Cr-Commit-Position: refs/heads/main@{#988274}

base/allocator/partition_allocator/partition_page.h

@@ -85,7 +85,7 @@ ALWAYS_INLINE uintptr_t SuperPagesEndFromExtent(
          (extent->number_of_consecutive_super_pages * kSuperPageSize);
 }
 
-using AllocationStateMap = ::base::internal::
+using AllocationStateMap =
     StateBitmap<kSuperPageSize, kSuperPageAlignment, kAlignment>;
 
 // Metadata of the slot span.

base/allocator/partition_allocator/starscan/state_bitmap.h

@@ -19,8 +19,7 @@
 #include "base/bits.h"
 #include "base/compiler_specific.h"
 
-namespace base {
-namespace internal {
+namespace partition_alloc::internal {
 
 // Bitmap which tracks allocation states. An allocation can be in one of 3
 // states:
@@ -70,7 +69,7 @@ class StateBitmap final {
   using CellType = uintptr_t;
   static constexpr size_t kBitsPerCell = sizeof(CellType) * CHAR_BIT;
   static constexpr size_t kBitsNeededForAllocation =
-      bits::Log2Floor(static_cast<size_t>(State::kNumOfStates));
+      base::bits::Log2Floor(static_cast<size_t>(State::kNumOfStates));
   static constexpr CellType kStateMask = (1 << kBitsNeededForAllocation) - 1;
 
   static constexpr size_t kBitmapSize =
@@ -483,7 +482,6 @@ void StateBitmap<PageSize, PageAlignment, AllocationAlignment>::Clear() {
   std::fill(bitmap_.begin(), bitmap_.end(), '\0');
 }
 
-}  // namespace internal
-}  // namespace base
+}  // namespace partition_alloc::internal
 
 #endif  // BASE_ALLOCATOR_PARTITION_ALLOCATOR_STARSCAN_STATE_BITMAP_H_

base/allocator/partition_allocator/starscan/state_bitmap_unittest.cc

@@ -10,8 +10,7 @@
 #include "base/allocator/partition_allocator/partition_alloc_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace base {
-namespace internal {
+namespace partition_alloc::internal {
 
 namespace {
 
@@ -340,5 +339,4 @@ TEST_F(PartitionAllocStateBitmapTest, AdjacentQuarantinedObjectsAtEnd) {
   }
 }
 
-}  // namespace internal
-}  // namespace base
+}  // namespace partition_alloc::internal