Split cc/base into separate GN source_set and clean deps

cc/trees/swap_promise_monitor.h

Index: cc/trees/swap_promise_monitor.h
diff --git a/cc/base/swap_promise_monitor.h b/cc/trees/swap_promise_monitor.h
similarity index 92%
rename from cc/base/swap_promise_monitor.h
rename to cc/trees/swap_promise_monitor.h
index cf06bee24492f6a4f97b6e3802b6725216808a6c..d163af58df3266ccafe24694f341bcd61bf6b9e5 100644
--- a/cc/base/swap_promise_monitor.h
+++ b/cc/trees/swap_promise_monitor.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CC_BASE_SWAP_PROMISE_MONITOR_H_
-#define CC_BASE_SWAP_PROMISE_MONITOR_H_
+#ifndef CC_TREES_SWAP_PROMISE_MONITOR_H_
+#define CC_TREES_SWAP_PROMISE_MONITOR_H_
 
 #include "cc/base/cc_export.h"
 
@@ -42,4 +42,4 @@ class CC_EXPORT SwapPromiseMonitor {
 
 }  // namespace cc
 
-#endif  // CC_BASE_SWAP_PROMISE_MONITOR_H_
+#endif  // CC_TREES_SWAP_PROMISE_MONITOR_H_