Bug 1566389 - Allow removing elements at the end of an AlignedAudioBuffer. r=jya

Differential Revision: https://phabricator.services.mozilla.com/D91776

dom/media/MediaData.h

@@ -187,6 +187,11 @@ class AlignedBuffer {
     mLength -= aSize;
   }
 
+  void PopBack(size_t aSize) {
+    MOZ_DIAGNOSTIC_ASSERT(mLength >= aSize, "Popping too many frames");
+    mLength -= aSize;
+  }
+
  private:
   static size_t AlignmentOffset() { return Alignment ? Alignment - 1 : 0; }