PartitionAlloc: Remove dead code

The bucket index lookup is now initialized at compile-time.

Change-Id: I13b7d09d88060f35d2f64197b5fbbd59c3102179
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2580798
Auto-Submit: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834983}

base/allocator/partition_allocator/partition_root.cc

@@ -305,13 +305,6 @@ static void PartitionDumpBucketStats(
 
 }  // namespace internal
 
-// TODO(lizeb): Consider making this constexpr. Without C++17 std::array, this
-// requires some template magic, only do it if it helps performance.
-template <bool thread_safe>
-uint16_t PartitionRoot<thread_safe>::bucket_index_lookup[((kBitsPerSizeT + 1) *
-                                                          kNumBucketsPerOrder) +
-                                                         1];
-
 template <bool thread_safe>
 NOINLINE void PartitionRoot<thread_safe>::OutOfMemory(size_t size) {
 #if !defined(ARCH_CPU_64_BITS)

base/allocator/partition_allocator/partition_root.h

@@ -161,13 +161,6 @@ struct BASE_EXPORT PartitionRoot {
   // path of the central allocator.
   internal::MaybeSpinLock<thread_safe> lock_;
 
-  // The bucket lookup table lets us map a size_t to a bucket quickly.
-  // The trailing +1 caters for the overflow case for very large allocation
-  // sizes.  It is one flat array instead of a 2D array because in the 2D
-  // world, we'd need to index array[blah][max+1] which risks undefined
-  // behavior.
-  static uint16_t
-      bucket_index_lookup[((kBitsPerSizeT + 1) * kNumBucketsPerOrder) + 1];
   Bucket buckets[kNumBuckets] = {};
   Bucket sentinel_bucket;