gamepad: explicitly delete copy/assign

DISALLOW_COPY_AND_ASSIGN is deprecated:
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++-dos-and-donts.md#explicitly-declare-class-copyability_movability

Change-Id: I384bdf3376d01834b6aa60ac202a9e7c368a869d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2105271Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Brandon Jones <bajones@chromium.org>
Auto-Submit: Johann Koenig <johannkoenig@google.com>
Cr-Commit-Position: refs/heads/master@{#751815}

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

@@ -37,6 +37,10 @@ class GamepadSharedMemoryReader : public device::mojom::blink::GamepadObserver {
   void Start(blink::GamepadListener* listener);
   void Stop();
 
+  GamepadSharedMemoryReader(const GamepadSharedMemoryReader&) = delete;
+  GamepadSharedMemoryReader& operator=(const GamepadSharedMemoryReader&) =
+      delete;
+
  protected:
   void SendStartMessage();
   void SendStopMessage();
@@ -59,8 +63,6 @@ class GamepadSharedMemoryReader : public device::mojom::blink::GamepadObserver {
   mojo::Receiver<device::mojom::blink::GamepadObserver> receiver_{this};
   mojo::Remote<device::mojom::blink::GamepadMonitor> gamepad_monitor_remote_;
   blink::GamepadListener* listener_ = nullptr;
-
-  DISALLOW_COPY_AND_ASSIGN(GamepadSharedMemoryReader);
 };
 
 }  // namespace blink