Fix webkit_tests by adding two more interfaces they expect.

TBR=rockot@chromium.org,tsepez@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2339703003
Cr-Commit-Position: refs/heads/master@{#418600}

content/public/app/mojo/content_browser_manifest.json

@@ -9,9 +9,11 @@
       "all_interfaces": [ "*" ],
       "web": [
         "blink::mojom::BackgroundSyncService",
+        "blink::mojom::BroadcastChannelProvider",
         "blink::mojom::BudgetService",
         "blink::mojom::MimeRegistry",
         "blink::mojom::NotificationService",
+        "blink::mojom::OffscreenCanvasFrameReceiver",
         "blink::mojom::OffscreenCanvasSurface",
         "blink::mojom::PermissionService",
         "blink::mojom::WebSocket",