[fuzzing] Allow memory quota fuzzer to supply config (#33243)

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---------

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

test/core/resource_quota/BUILD

@@ -150,6 +150,7 @@ grpc_proto_fuzzer(
     ],
     language = "C++",
     proto = "memory_quota_fuzzer.proto",
+    proto_deps = ["//test/core/util:fuzz_config_vars_proto"],
     tags = ["no_windows"],
     uses_event_engine = False,
     uses_polling = False,
@@ -162,7 +163,9 @@ grpc_proto_fuzzer(
         "//src/core:closure",
         "//src/core:error",
         "//src/core:event_engine_memory_allocator",
+        "//src/core:experiments",
         "//src/core:memory_quota",
         "//src/core:useful",
+        "//test/core/util:fuzz_config_vars",
     ],
 )

test/core/resource_quota/memory_quota_fuzzer.cc

@@ -30,6 +30,7 @@
 #include <grpc/support/log.h>
 
 #include "src/core/lib/debug/trace.h"
+#include "src/core/lib/experiments/config.h"
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/gprpp/debug_location.h"
 #include "src/core/lib/iomgr/closure.h"
@@ -39,6 +40,7 @@
 #include "src/libfuzzer/libfuzzer_macro.h"
 #include "test/core/resource_quota/call_checker.h"
 #include "test/core/resource_quota/memory_quota_fuzzer.pb.h"
+#include "test/core/util/fuzz_config_vars.h"
 
 bool squelch = true;
 bool leak_check = true;
@@ -190,6 +192,8 @@ static void dont_log(gpr_log_func_args* /*args*/) {}
 
 DEFINE_PROTO_FUZZER(const memory_quota_fuzzer::Msg& msg) {
   if (squelch) gpr_set_log_function(dont_log);
+  grpc_core::ApplyFuzzConfigVars(msg.config_vars());
+  grpc_core::TestOnlyReloadExperimentsFromConfigVariables();
   gpr_log_verbosity_init();
   grpc_tracer_init();
   grpc_core::testing::Fuzzer().Run(msg);

test/core/resource_quota/memory_quota_fuzzer.proto

@@ -16,6 +16,8 @@ syntax = "proto3";
 
 package memory_quota_fuzzer;
 
+import "test/core/util/fuzz_config_vars.proto";
+
 message Empty {}
 
 message Reclaimer {
@@ -54,4 +56,5 @@ message Action {
 
 message Msg {
     repeated Action actions = 2;
+    grpc.testing.FuzzConfigVars config_vars = 3;
 }