Tab Search: Adds a UMA histogram to collect API performance

This CL adds a UMA histogram to track the API performance of the
getTabs() API for TabSearch.

Matching WebUI CL below:
https://chrome-internal-review.googlesource.com/c/chrome/browser/resources/tab_search/+/3291206

Bug: 1099917
Change-Id: I8ddfddd5197f0d0641a3dcc3bf6c86fe118c07fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2432589
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811727}

tools/metrics/histograms/histograms_xml/tab/histograms.xml

@@ -1817,6 +1817,19 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Tabs.TabSearch.WebUI.TabListDataReceived" units="ms"
+    expires_after="M90">
+  <owner>tluk@chromium.org</owner>
+  <owner>robliao@chromium.org</owner>
+  <owner>yuhengh@chromium.org</owner>
+  <summary>
+    The time taken for the WebUI in the renderer to receive the full list of
+    tabs for the current user profile. This is measured as the time from when
+    the data was first requested by the WebUI to when the data was received by
+    the WebUI.
+  </summary>
+</histogram>
+
 <histogram name="Tabs.TabSearch.WebUI.TabSwitchAction"
     enum="TabSearchTabSwitchAction" expires_after="M90">
   <owner>tluk@chromium.org</owner>