Move tracing namespace from base::debug to base::trace_event.

cc/output/filter_operations.h

Index: cc/output/filter_operations.h
diff --git a/cc/output/filter_operations.h b/cc/output/filter_operations.h
index a8c206eacd1b0593cfc3f4400420d9f3ae63c4e0..d7e4e87b9771ef7b936baeefd386a7cb138f8486 100644
--- a/cc/output/filter_operations.h
+++ b/cc/output/filter_operations.h
@@ -12,11 +12,18 @@
 #include "cc/output/filter_operation.h"
 
 namespace base {
-namespace debug {
+namespace trace_event {
 class TracedValue;
 }
-class Value;
+
+// This is added temporarily. Once the renaming of namespace usages
+// accross all folders are done, this will be removed.
+// TODO(ssid): crrev.com/837303004
+namespace debug {
+using ::base::trace_event::TracedValue;
 }
+class Value;
+}  // namespace base
 
 namespace cc {