[cleanup] Make ownership in the ArrayBufferCollector clearer

The allocations vector does not need to be dynamically allocated, we can
just std::move it around instead.

Change-Id: If38af59deeccc06005397f255e18a2fa1bdf4298
Reviewed-on: https://chromium-review.googlesource.com/1099063
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53727}

src/heap/array-buffer-collector.cc

@@ -12,18 +12,18 @@ namespace v8 {
 namespace internal {
 
 void ArrayBufferCollector::AddGarbageAllocations(
-    std::vector<JSArrayBuffer::Allocation>* allocations) {
+    std::vector<JSArrayBuffer::Allocation> allocations) {
   base::LockGuard<base::Mutex> guard(&allocations_mutex_);
-  allocations_.push_back(allocations);
+  allocations_.push_back(std::move(allocations));
 }
 
 void ArrayBufferCollector::FreeAllocations() {
   base::LockGuard<base::Mutex> guard(&allocations_mutex_);
-  for (std::vector<JSArrayBuffer::Allocation>* allocations : allocations_) {
-    for (auto alloc : *allocations) {
+  for (const std::vector<JSArrayBuffer::Allocation>& allocations :
+       allocations_) {
+    for (JSArrayBuffer::Allocation alloc : allocations) {
       JSArrayBuffer::FreeBackingStore(heap_->isolate(), alloc);
     }
-    delete allocations;
   }
   allocations_.clear();
 }

src/heap/array-buffer-collector.h

@@ -28,7 +28,7 @@ class ArrayBufferCollector {
   // These allocations will begin to be freed once FreeAllocations() is called,
   // or on TearDown.
   void AddGarbageAllocations(
-      std::vector<JSArrayBuffer::Allocation>* allocations);
+      std::vector<JSArrayBuffer::Allocation> allocations);
 
   // Calls FreeAllocations() on a background thread.
   void FreeAllocationsOnBackgroundThread();
@@ -42,7 +42,7 @@ class ArrayBufferCollector {
 
   Heap* heap_;
   base::Mutex allocations_mutex_;
-  std::vector<std::vector<JSArrayBuffer::Allocation>*> allocations_;
+  std::vector<std::vector<JSArrayBuffer::Allocation>> allocations_;
 };
 
 }  // namespace internal

src/heap/array-buffer-tracker.cc

@@ -20,8 +20,7 @@ LocalArrayBufferTracker::~LocalArrayBufferTracker() {
 
 template <typename Callback>
 void LocalArrayBufferTracker::Process(Callback callback) {
-  std::vector<JSArrayBuffer::Allocation>* backing_stores_to_free =
-      new std::vector<JSArrayBuffer::Allocation>();
+  std::vector<JSArrayBuffer::Allocation> backing_stores_to_free;
 
   JSArrayBuffer* new_buffer = nullptr;
   JSArrayBuffer* old_buffer = nullptr;
@@ -54,7 +53,7 @@ void LocalArrayBufferTracker::Process(Callback callback) {
       // We pass backing_store() and stored length to the collector for freeing
       // the backing store. Wasm allocations will go through their own tracker
       // based on the backing store.
-      backing_stores_to_free->emplace_back(
+      backing_stores_to_free.emplace_back(
           old_buffer->backing_store(), it->second, old_buffer->backing_store(),
           old_buffer->allocation_mode(), old_buffer->is_wasm_memory());
       it = array_buffers_.erase(it);
@@ -73,9 +72,8 @@ void LocalArrayBufferTracker::Process(Callback callback) {
 
   // Pass the backing stores that need to be freed to the main thread for later
   // distribution.
-  // ArrayBufferCollector takes ownership of this pointer.
   space_->heap()->array_buffer_collector()->AddGarbageAllocations(
-      backing_stores_to_free);
+      std::move(backing_stores_to_free));
 }
 
 void ArrayBufferTracker::PrepareToFreeDeadInNewSpace(Heap* heap) {