Fix leak of message snapshot buffer when attempting to send an illegal object.

runtime/vm/benchmark_test.cc

Index: runtime/vm/benchmark_test.cc
diff --git a/runtime/vm/benchmark_test.cc b/runtime/vm/benchmark_test.cc
index e2f8790357fc229a2466f3a964be18356b71fa99..efe1223e82132d0ba46e666154bae3b4acc910a0 100644
--- a/runtime/vm/benchmark_test.cc
+++ b/runtime/vm/benchmark_test.cc
@@ -491,6 +491,11 @@ static uint8_t* malloc_allocator(uint8_t* ptr,
 }
 
 
+static void malloc_deallocator(uint8_t* ptr) {
+  free(ptr);
+}
+
+
 BENCHMARK_SIZE(CoreSnapshotSize) {
   const char* kScriptChars =
       "import 'dart:async';\n"
@@ -607,6 +612,7 @@ static uint8_t* message_allocator(uint8_t* ptr,
                                   intptr_t new_size) {
   return message_buffer;
 }
+static void message_deallocator(uint8_t* ptr) {}
 
 
 BENCHMARK(SerializeNull) {
@@ -617,7 +623,8 @@ BENCHMARK(SerializeNull) {
   timer.Start();
   for (intptr_t i = 0; i < kLoopCount; i++) {
     StackZone zone(thread);
-    MessageWriter writer(&buffer, &message_allocator, true);
+    MessageWriter writer(&buffer, &message_allocator, &message_deallocator,
+                         true);
     writer.WriteMessage(null_object);
     intptr_t buffer_len = writer.BytesWritten();
 
@@ -639,7 +646,8 @@ BENCHMARK(SerializeSmi) {
   timer.Start();
   for (intptr_t i = 0; i < kLoopCount; i++) {
     StackZone zone(thread);
-    MessageWriter writer(&buffer, &message_allocator, true);
+    MessageWriter writer(&buffer, &message_allocator, &message_deallocator,
+                         true);
     writer.WriteMessage(smi_object);
     intptr_t buffer_len = writer.BytesWritten();
 
@@ -664,7 +672,7 @@ BENCHMARK(SimpleMessage) {
   timer.Start();
   for (intptr_t i = 0; i < kLoopCount; i++) {
     StackZone zone(thread);
-    MessageWriter writer(&buffer, &malloc_allocator, true);
+    MessageWriter writer(&buffer, &malloc_allocator, &malloc_deallocator, true);
     writer.WriteMessage(array_object);
     intptr_t buffer_len = writer.BytesWritten();
 
@@ -698,7 +706,7 @@ BENCHMARK(LargeMap) {
   timer.Start();
   for (intptr_t i = 0; i < kLoopCount; i++) {
     StackZone zone(thread);
-    MessageWriter writer(&buffer, &malloc_allocator, true);
+    MessageWriter writer(&buffer, &malloc_allocator, &malloc_deallocator, true);
     writer.WriteMessage(map);
     intptr_t buffer_len = writer.BytesWritten();