Convert Gamepad IPC messages into mojo interface.

content/public/app/mojo/content_browser_manifest.json

 {
   "name": "content_browser",
   "display_name": "Content (browser process)",
   "interface_provider_specs": {
     "service_manager:connector": {
       "provides": {
         "gpu": [
           "device::mojom::PowerMonitor"
         ],
         "plugin": [
@@ skipping 11 matching lines @@
           "blink::mojom::OffscreenCanvasCompositorFrameSinkProvider",
           "blink::mojom::OffscreenCanvasSurface",
           "blink::mojom::PermissionService",
           "blink::mojom::WebSocket",
           "content::mojom::MemoryCoordinatorHandle",
           "content::mojom::ServiceWorkerDispatcherHost",
           "content::mojom::StoragePartitionService",
           "content::mojom::URLLoaderFactory",
           "content::mojom::VideoCaptureHost",
           "device::BatteryMonitor",
+          "device::mojom::GamepadMonitor",
           "device::mojom::LightSensor",
           "device::mojom::MotionSensor",
           "device::mojom::OrientationSensor",
           "device::mojom::PowerMonitor",
           "device::mojom::TimeZoneMonitor",
           "media::mojom::ImageCapture",
           "memory_coordinator::mojom::MemoryCoordinatorHandle",
           "payments::mojom::PaymentAppManager"
         ],
         "service_manager:service_factory": [
@@ skipping 48 matching lines @@
           "mojom::MediaDevicesDispatcherHost",
           "payments::mojom::PaymentRequest"
         ]
       },
       "requires": {
         "content_renderer": [ "browser" ]
       }
     }
   }
 }