Replaced cc::SurfaceId::nonce_ with base::UnguessableToken

cc/ipc/surface_id.mojom

Index: cc/ipc/surface_id.mojom
diff --git a/cc/ipc/surface_id.mojom b/cc/ipc/surface_id.mojom
index 0a0e5fa903fadeef752b8a411f9687da5b54c6c0..2e76ab304e18dec3782818e8603b92213617b6d2 100644
--- a/cc/ipc/surface_id.mojom
+++ b/cc/ipc/surface_id.mojom
@@ -4,6 +4,8 @@
 
 module cc.mojom;
 
+import "mojo/common/common_custom_types.mojom";
+
 // A surface ID is composed of three parts: a client ID, a local ID, and a
 // nonce. The local part and nonce are allocated by the client using any scheme
 // that avoids duplicates and makes IDs unguessable respectively. The client ID
@@ -24,5 +26,5 @@ struct SurfaceId {
 
   // A cryptographically secure random int chosen to make the SurfaceId
   // unguessable by other clients.
-  uint64 nonce;
+  mojo.common.mojom.UnguessableToken nonce;
 };