Update Surface ID Terminology

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 f4f7427274192535556dcae04a93fa0905aecc2d..0a0e5fa903fadeef752b8a411f9687da5b54c6c0 100644
--- a/cc/ipc/surface_id.mojom
+++ b/cc/ipc/surface_id.mojom
@@ -4,19 +4,19 @@
 
 module cc.mojom;
 
-// A surface ID is composed of three parts: a namespace, a local ID, and a
+// 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 namespace
+// that avoids duplicates and makes IDs unguessable respectively. The client ID
 // is allocated by the service and will be different for each client.
 //
-// The special id_namespace value 0 is equivalent to the namespace of the
-// client. This can be used to create, destroy and submit frames to
-// surfaces before learning the namespace and to reference other surfaces
-// owned by the same client. The actual id namespace must be used to pass
-// surface ids to other clients for them to reference.
+// The special client_id value 0 is equivalent to the current client.
+// This can be used to create, destroy and submit frames to surfaces before
+// learning the client ID and to reference other surfaces owned by the same
+// client. The actual client ID must be used to pass surface ids to other
+// clients for them to reference.
 struct SurfaceId {
   // A service allocated ID identifying a client.
-  uint32 id_namespace;
+  uint32 client_id;
 
   // An identifier allocated by the client uniquely identifying a surface within
   // a client process.