Tab Search: Add trace events to measure performance

Bug: 1099917
Change-Id: I1f2a25b7ffb96cd89fd5e316d15c332be5222a27
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2406678Reviewed-by: John Lee <johntlee@chromium.org>
Commit-Queue: Yuheng Huang <yuhengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806360}

chrome/browser/ui/webui/tab_search/tab_search_page_handler.cc

@@ -13,6 +13,7 @@
 #include "base/metrics/histogram_functions.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
+#include "base/trace_event/trace_event.h"
 #include "chrome/browser/extensions/extension_tab_util.h"
 #include "chrome/browser/favicon/favicon_utils.h"
 #include "chrome/browser/ui/browser.h"
@@ -72,6 +73,7 @@ void TabSearchPageHandler::CloseTab(int32_t tab_id) {
 }
 
 void TabSearchPageHandler::GetProfileTabs(GetProfileTabsCallback callback) {
+  TRACE_EVENT0("browser", "TabSearchPageHandler::GetProfileTabs");
   auto profile_tabs = tab_search::mojom::ProfileTabs::New();
   Profile* profile = browser_->profile();
   for (auto* browser : *BrowserList::GetInstance()) {
@@ -207,6 +209,7 @@ void TabSearchPageHandler::TabChangedAt(content::WebContents* contents,
   Browser* browser = chrome::FindBrowserWithWebContents(contents);
   if (!browser)
     return;
+  TRACE_EVENT0("browser", "TabSearchPageHandler::TabChangedAt");
   page_->TabUpdated(GetTabData(browser->tab_strip_model(), contents, index));
 }