Add PDF compositor service

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 31 matching lines @@
           "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": [
+          "discardable_memory::mojom::DiscardableSharedMemoryManager",
           "memory_instrumentation::mojom::Coordinator"
         ]
       },
       "requires": {
         "*": [ "app" ],
         // In classic ash, the browser supplies ash interfaces to itself.
         "content_browser": [ "ash" ],
         "content_gpu": [ "browser" ],
         "content_plugin": [ "browser" ],
         "content_renderer": [ "browser" ],
@@ skipping 49 matching lines @@
           "payments::mojom::PaymentRequest",
           "ui::mojom::Gpu"
         ]
       },
       "requires": {
         "content_renderer": [ "browser" ]
       }
     }
   }
 }