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

cc/resources/tile_manager.h

Index: cc/resources/tile_manager.h
diff --git a/cc/resources/tile_manager.h b/cc/resources/tile_manager.h
index f945f7c0088617a1f0a46cc74df457cbd2d15707..873751e3aed363ccb2122281d1751757cc7f2500 100644
--- a/cc/resources/tile_manager.h
+++ b/cc/resources/tile_manager.h
@@ -26,11 +26,19 @@
 #include "cc/resources/tile_task_runner.h"
 
 namespace base {
-namespace debug {
+namespace trace_event {
 class ConvertableToTraceFormat;
 class TracedValue;
 }
+
+// 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::ConvertableToTraceFormat;
+using ::base::trace_event::TracedValue;
 }
+}  // namespace base
 
 namespace cc {
 class PictureLayerImpl;