Bug 1842658 - Part 2: Use refcounting macros for nsHtml5OwningUTF16Buffer, r=mccr8

When the code was originally added in bug 1842658, it was to use non-atomic
refcounting across multiple threads due to some invariants preventing
concurrent access. That was changed in bug 1607762 to fix a race issue.

We should be able to switch to using the macros now, which will simplify the
code here a bit.

Depends on D183203

Differential Revision: https://phabricator.services.mozilla.com/D183204

parser/html/nsHtml5OwningUTF16Buffer.cpp

@@ -55,25 +55,3 @@ Span<char16_t> nsHtml5OwningUTF16Buffer::TailAsSpan(int32_t aBufferSize) {
 void nsHtml5OwningUTF16Buffer::AdvanceEnd(int32_t aNumberOfCodeUnits) {
   setEnd(getEnd() + aNumberOfCodeUnits);
 }
-
-// Not using macros for AddRef and Release in order to be able to refcount on
-// and create on different threads.
-
-nsrefcnt nsHtml5OwningUTF16Buffer::AddRef() {
-  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "Illegal refcount.");
-  ++mRefCnt;
-  NS_LOG_ADDREF(this, mRefCnt, "nsHtml5OwningUTF16Buffer", sizeof(*this));
-  return mRefCnt;
-}
-
-nsrefcnt nsHtml5OwningUTF16Buffer::Release() {
-  MOZ_ASSERT(0 != mRefCnt, "Release without AddRef.");
-  --mRefCnt;
-  NS_LOG_RELEASE(this, mRefCnt, "nsHtml5OwningUTF16Buffer");
-  if (mRefCnt == 0) {
-    mRefCnt = 1; /* stabilize */
-    delete this;
-    return 0;
-  }
-  return mRefCnt;
-}

parser/html/nsHtml5OwningUTF16Buffer.h

@@ -9,6 +9,9 @@
 #include "mozilla/Span.h"
 
 class nsHtml5OwningUTF16Buffer : public nsHtml5UTF16Buffer {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsHtml5OwningUTF16Buffer)
+
  private:
   /**
    * Passes a buffer and its length to the superclass constructor.
@@ -56,12 +59,6 @@ class nsHtml5OwningUTF16Buffer : public nsHtml5UTF16Buffer {
    * Add the argument to `end`.
    */
   void AdvanceEnd(int32_t aNumberOfCodeUnits);
-
-  nsrefcnt AddRef();
-  nsrefcnt Release();
-
- private:
-  mozilla::ThreadSafeAutoRefCnt mRefCnt;
 };
 
 #endif  // nsHtml5OwningUTF16Buffer_h