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

cc/surfaces/surface_id_allocator.cc

Index: cc/surfaces/surface_id_allocator.cc
diff --git a/cc/surfaces/surface_id_allocator.cc b/cc/surfaces/surface_id_allocator.cc
index af4d5932df723a6da76dc79377e0430248785966..24bcfbd46f95e9e95a7af99b6c8769ab8dbb38cd 100644
--- a/cc/surfaces/surface_id_allocator.cc
+++ b/cc/surfaces/surface_id_allocator.cc
@@ -7,6 +7,7 @@
 #include <stdint.h>
 
 #include "base/rand_util.h"
+#include "base/unguessable_token.h"
 
 namespace cc {
 
@@ -16,8 +17,7 @@ SurfaceIdAllocator::~SurfaceIdAllocator() {
 }
 
 LocalFrameId SurfaceIdAllocator::GenerateId() {
-  uint64_t nonce = base::RandUint64();
-  LocalFrameId id(next_id_, nonce);
+  LocalFrameId id(next_id_, base::UnguessableToken::Create());
   next_id_++;
   return id;
 }