Fix a future warning that complains handle not get released properly.

In the FutureBase constructor, we detached the handle since already has the actual future instance to hold the reference count.

PiperOrigin-RevId: 315973013

Author: cynthiajiang

app/src/include/firebase/internal/future_impl.h

@@ -204,6 +204,8 @@ inline FutureBase::FutureBase(detail::FutureApiInterface* api,
                               const FutureHandle& handle)
     : api_(api), handle_(handle) {
   api_->ReferenceFuture(handle_);
+  // Once the FutureBase has reference, we don't need extra handle reference.
+  handle_.Detach();
   detail::RegisterForCleanup(api_, this);
 }
 

app/src/reference_counted_future_impl.cc

@@ -701,10 +701,9 @@ bool ReferenceCountedFutureImpl::IsReferencedExternally() const {
   }
   for (int i = 0; i < last_results_.size(); i++) {
     if (last_results_[i].status() != kFutureStatusInvalid) {
-      // If the status is not invalid, this entry is using up 2 references,
-      // one for the Future and one for the FutureHandle it holds.
+      // If the status is not invalid, this entry is using up a reference.
       // Count up the internal references.
-      internal_references += 2;
+      internal_references++;
     }
   }
   // If there are more references than the internal ones, someone is holding