Add support for single sample metrics.

content/public/app/mojo/content_browser_manifest.json

 {
   "name": "content_browser",
   "display_name": "Content (browser process)",
   "interface_provider_specs": {
     "service_manager:connector": {
       "provides": {
         "gpu": [
           "content::mojom::FieldTrialRecorder",
           "media::mojom::AndroidOverlayProvider",
           "memory_instrumentation::mojom::Coordinator"
@@ skipping 19 matching lines @@
           "content::mojom::FrameSinkProvider",
           "content::mojom::ServiceWorkerDispatcherHost",
           "content::mojom::StoragePartitionService",
           "content::mojom::URLLoaderFactory",
           "content::mojom::VideoCaptureHost",
           "device::mojom::GamepadMonitor",
           "discardable_memory::mojom::DiscardableSharedMemoryManager",
           "media::mojom::ImageCapture",
           "memory_coordinator::mojom::MemoryCoordinatorHandle",
           "memory_instrumentation::mojom::Coordinator",
+          "metrics::mojom::SingleValueHistogramsProvider",
           "payments::mojom::PaymentManager",
           "shape_detection::mojom::BarcodeDetection",
           "shape_detection::mojom::FaceDetectionProvider",
           "shape_detection::mojom::TextDetection",
           "ui::mojom::Gpu"
         ],
         "service_manager:service_factory": [
           "service_manager::mojom::ServiceFactory"
         ],
         "utility": [
@@ skipping 55 matching lines @@
           "payments::mojom::PaymentRequest",
           "ui::mojom::Gpu"
         ]
       },
       "requires": {
         "content_renderer": [ "browser" ]
       }
     }
   }
 }