Add traces for main omnibox providers

components/omnibox/browser/zero_suggest_provider.cc

Index: components/omnibox/browser/zero_suggest_provider.cc
diff --git a/components/omnibox/browser/zero_suggest_provider.cc b/components/omnibox/browser/zero_suggest_provider.cc
index 956c245276e0290e4a40100bcd5350a2d743b454..4a2043a6bcaf40955c0c80b8c03f8a9d86da3c2e 100644
--- a/components/omnibox/browser/zero_suggest_provider.cc
+++ b/components/omnibox/browser/zero_suggest_provider.cc
@@ -15,6 +15,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
 #include "components/data_use_measurement/core/data_use_user_data.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/top_sites.h"
@@ -85,6 +86,7 @@ void ZeroSuggestProvider::RegisterProfilePrefs(
 
 void ZeroSuggestProvider::Start(const AutocompleteInput& input,
                                 bool minimal_changes) {
+  TRACE_EVENT0("omnibox", "ZeroSuggestProvider::Start");
   matches_.clear();
   if (!input.from_omnibox_focus() ||
       input.type() == metrics::OmniboxInputType::INVALID)