Handle both plural and singular tab switcher content descriptions.

chrome/android/java/strings/android_chrome_strings.grd

Index: chrome/android/java/strings/android_chrome_strings.grd
diff --git a/chrome/android/java/strings/android_chrome_strings.grd b/chrome/android/java/strings/android_chrome_strings.grd
index b73ba6ebedea4fe60f607d494ce039a63fe0dad7..68df94e01a1ef3643b5e93f18f78765d56b89005 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -2318,8 +2318,11 @@ You are signing in with a managed account and giving its administrator control o
       <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_NEW_INCOGNITO_TAB" desc="Content description for the new incognito tab button.">
         New incognito tab
       </message>
-      <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_TABSWITCHER_TOGGLE" desc="Content description for the button that enters or leaves the tab switcher.">
-        <ph name="OPEN_TABS">%1$d<ex>3</ex></ph> open tabs
+      <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_TABSWITCHER_TOGGLE" desc="Content description for the button that enters or leaves the tab switcher. [ICU Syntax]">
+        {OPEN_TABS, plural, =1 {%1$d open tab} other {%1$d open tabs}}
+      </message>
+      <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_TABSWITCHER_TOGGLE_DEFAULT" desc="Placeholder content description for the button that enters or leaves the tab switcher.">
+        open tabs
       </message>
       <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_HOME" desc="Content description for the home button.">
         Home