Use HpackEntry::Size() instead of rolling our own in QpackDynamicTable.

(Note that QpackEntry is an alias for HpackEntry.)

I'm a little uncomfortable with HpackEntry::Size() returning size_t instead of
uint64_t, because Chromium supports platforms where size_t is uint32_t and
sometimes funny things happen, especially with UBSAN around type conversions.
The reason for returning size_t is that is string_view::size_type and
std::string::size_type.  In practice we'll never deal with long strings so
this should really not be a problem.

This came up because I will need to access EntrySize() from outside
QpackHeaderTable and it makes more sense to use HpackEntry::Size() consistently
then to make EntrySize() public.

gfe-relnote: n/a, QUIC v99-only code.
PiperOrigin-RevId: 257903243
Change-Id: I354ffb46a9a6d7e2e4f2ba2d581115f6c0f4cfd5

quic/core/qpack/qpack_header_table.cc

diff --git a/quic/core/qpack/qpack_header_table.cc b/quic/core/qpack/qpack_header_table.cc
index 9522666..6fa6412 100644
--- a/quic/core/qpack/qpack_header_table.cc
+++ b/quic/core/qpack/qpack_header_table.cc
@@ -9,16 +9,6 @@
 
 namespace quic {
 
-namespace {
-
-const uint64_t kEntrySizeOverhead = 32;
-
-uint64_t EntrySize(QuicStringPiece name, QuicStringPiece value) {
-  return name.size() + value.size() + kEntrySizeOverhead;
-}
-
-}  // anonymous namespace
-
 QpackHeaderTable::QpackHeaderTable()
     : static_entries_(ObtainQpackStaticTable().GetStaticEntries()),
       static_index_(ObtainQpackStaticTable().GetStaticIndex()),
@@ -102,7 +92,7 @@
 
 const QpackEntry* QpackHeaderTable::InsertEntry(QuicStringPiece name,
                                                 QuicStringPiece value) {
-  const uint64_t entry_size = EntrySize(name, value);
+  const uint64_t entry_size = QpackEntry::Size(name, value);
   if (entry_size > dynamic_table_capacity_) {
     return nullptr;
   }
@@ -193,7 +183,7 @@
     DCHECK(!dynamic_entries_.empty());
 
     QpackEntry* const entry = &dynamic_entries_.front();
-    const uint64_t entry_size = EntrySize(entry->name(), entry->value());
+    const uint64_t entry_size = entry->Size();
 
     DCHECK_GE(dynamic_table_size_, entry_size);
     dynamic_table_size_ -= entry_size;