[iOS] Add metric for the NewTab button

This CL adds a metric to differentiate the omnibox shortcut and the
NewTab shortcut.

Fixed: 1025115
Change-Id: I4469813bb08b1f6c3e372afca18e6d75d90ef04d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1917370
Auto-Submit: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Nik Bhagat <nikunjb@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718717}

ios/chrome/browser/ui/toolbar/adaptive_toolbar_view_controller.mm

@@ -387,7 +387,13 @@ const CGFloat kTabGridAnimationsTotalDuration = 0.5;
   } else if (sender == self.view.shareButton) {
     base::RecordAction(base::UserMetricsAction("MobileToolbarShareMenu"));
   } else if (sender == self.view.searchButton) {
-    base::RecordAction(base::UserMetricsAction("MobileToolbarOmniboxShortcut"));
+    if (base::FeatureList::IsEnabled(kToolbarNewTabButton)) {
+      base::RecordAction(
+          base::UserMetricsAction("MobileToolbarNewTabShortcut"));
+    } else {
+      base::RecordAction(
+          base::UserMetricsAction("MobileToolbarOmniboxShortcut"));
+    }
   } else {
     NOTREACHED();
   }

tools/metrics/actions/actions.xml

@@ -13735,6 +13735,14 @@ should be able to be added at any place in this file.
   <description>Please enter the description of this user action.</description>
 </action>
 
+<action name="MobileToolbarNewTabShortcut">
+  <owner>gambard@chromium.org</owner>
+  <owner>stkhapugin@chromium.org</owner>
+  <description>
+    User pressed the NewTab shortcut on the toolbar. iOS only.
+  </description>
+</action>
+
 <action name="MobileToolbarOmniboxAcceleratorTap">
   <owner>mdjones@chromium.org</owner>
   <owner>chrome-android-apps@chromium.org</owner>