Deprecate FLAGS_quic_enable_arena_allocation.

net/quic/quic_arena_scoped_ptr_test.cc

Index: net/quic/quic_arena_scoped_ptr_test.cc
diff --git a/net/quic/quic_arena_scoped_ptr_test.cc b/net/quic/quic_arena_scoped_ptr_test.cc
index d9ce1b15752aef14ccdb7bd4e8cfffafd122e631..9ba2e3d165c64ad94075f86397e4b93362cd7d41 100644
--- a/net/quic/quic_arena_scoped_ptr_test.cc
+++ b/net/quic/quic_arena_scoped_ptr_test.cc
@@ -24,8 +24,6 @@ struct TestObject {
 
 class QuicArenaScopedPtrParamTest : public ::testing::TestWithParam<TestParam> {
  protected:
-  QuicArenaScopedPtrParamTest() { FLAGS_quic_enable_arena_allocation = true; }
-
   QuicArenaScopedPtr<TestObject> CreateObject(uintptr_t value) {
     QuicArenaScopedPtr<TestObject> ptr;
     switch (GetParam()) {
@@ -51,7 +49,6 @@ INSTANTIATE_TEST_CASE_P(QuicArenaScopedPtrParamTest,
                                         TestParam::kFromArena));
 
 TEST(QuicArenaScopedPtrTest, NullObjects) {
-  FLAGS_quic_enable_arena_allocation = true;
   QuicArenaScopedPtr<TestObject> def;
   QuicArenaScopedPtr<TestObject> null(nullptr);
   EXPECT_EQ(def, null);
@@ -60,7 +57,6 @@ TEST(QuicArenaScopedPtrTest, NullObjects) {
 }
 
 TEST(QuicArenaScopedPtrTest, FromArena) {
-  FLAGS_quic_enable_arena_allocation = true;
   QuicOneBlockArena<1024> arena_;
   EXPECT_TRUE(arena_.New<TestObject>(0).is_from_arena());
   EXPECT_FALSE(