heap mojo: add mode to gamepad shared memory reader

The new wrapper changed the behavior slightly during the migration. The
wrapper defines a default ContextDestroyed method. If some other cleanup
method tries to access receiver_ it may crash. This change reverts to
the pre-migration behavior.

BUG=chromium:1049056

Change-Id: I9feafcf13c732664e8b10b6cba1a5258e3012e22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2131803Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Johann Koenig <johannkoenig@google.com>
Cr-Commit-Position: refs/heads/master@{#755569}

third_party/blink/renderer/modules/gamepad/gamepad_shared_memory_reader.h

@@ -14,6 +14,7 @@
 #include "mojo/public/cpp/system/buffer.h"
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/mojo/heap_mojo_receiver.h"
+#include "third_party/blink/renderer/platform/mojo/heap_mojo_wrapper_mode.h"
 
 namespace base {
 class ReadOnlySharedMemoryRegion;
@@ -64,7 +65,9 @@ class GamepadSharedMemoryReader
 
   bool ever_interacted_with_ = false;
 
-  HeapMojoReceiver<device::mojom::blink::GamepadObserver> receiver_;
+  HeapMojoReceiver<device::mojom::blink::GamepadObserver,
+                   HeapMojoWrapperMode::kWithoutContextObserver>
+      receiver_;
   mojo::Remote<device::mojom::blink::GamepadMonitor> gamepad_monitor_remote_;
   blink::GamepadListener* listener_ = nullptr;
 };