tracing: simplify lifetime of TraceEventFilter(s)

base/trace_event/event_name_filter_unittest.cc

Index: base/trace_event/event_name_filter_unittest.cc
diff --git a/base/trace_event/event_name_filter_unittest.cc b/base/trace_event/event_name_filter_unittest.cc
index 0bc2a4dafcf8f4c4e59047e1469aaea68548fa4c..88d61f197a9dc92b03459eb1101e86714dcf0a74 100644
--- a/base/trace_event/event_name_filter_unittest.cc
+++ b/base/trace_event/event_name_filter_unittest.cc
@@ -21,7 +21,8 @@ const TraceEvent& MakeTraceEvent(const char* name) {
 
 TEST(TraceEventNameFilterTest, Whitelist) {
   auto empty_whitelist = MakeUnique<EventNameFilter::EventNamesWhitelist>();
-  auto filter = MakeUnique<EventNameFilter>(std::move(empty_whitelist));
+  std::unique_ptr<EventNameFilter> filter;
+  filter = MakeUnique<EventNameFilter>(nullptr, std::move(empty_whitelist));
 
   // No events should be filtered if the whitelist is empty.
   EXPECT_FALSE(filter->FilterTraceEvent(MakeTraceEvent("foo")));
@@ -29,7 +30,7 @@ TEST(TraceEventNameFilterTest, Whitelist) {
   auto whitelist = MakeUnique<EventNameFilter::EventNamesWhitelist>();
   whitelist->insert("foo");
   whitelist->insert("bar");
-  filter = MakeUnique<EventNameFilter>(std::move(whitelist));
+  filter = MakeUnique<EventNameFilter>(nullptr, std::move(whitelist));
   EXPECT_TRUE(filter->FilterTraceEvent(MakeTraceEvent("foo")));
   EXPECT_FALSE(filter->FilterTraceEvent(MakeTraceEvent("fooz")));
   EXPECT_FALSE(filter->FilterTraceEvent(MakeTraceEvent("afoo")));