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

base/trace_event/trace_event_argument.h

Index: base/trace_event/trace_event_argument.h
diff --git a/base/trace_event/trace_event_argument.h b/base/trace_event/trace_event_argument.h
index 08a5b50057f81735af1edc2c06fa6880553e0d5b..f4c35f81a6679277ab1fceb9ee5f0c13ece32e2f 100644
--- a/base/trace_event/trace_event_argument.h
+++ b/base/trace_event/trace_event_argument.h
@@ -16,7 +16,7 @@ class DictionaryValue;
 class ListValue;
 class Value;
 
-namespace debug {
+namespace trace_event {
 
 class BASE_EXPORT TracedValue : public ConvertableToTraceFormat {
  public:
@@ -53,6 +53,15 @@ class BASE_EXPORT TracedValue : public ConvertableToTraceFormat {
   DISALLOW_COPY_AND_ASSIGN(TracedValue);
 };
 
+}  // namespace trace_event
+}  // namespace base
+
+// 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 base {
+namespace debug {
+using base::trace_event::TracedValue;
 }  // namespace debug
 }  // namespace base