[Signin iOS] Update title in merging data dialog

ios/chrome/app/strings/ios_strings.grd

Index: ios/chrome/app/strings/ios_strings.grd
diff --git a/ios/chrome/app/strings/ios_strings.grd b/ios/chrome/app/strings/ios_strings.grd
index deb1a90e6a8733c7785d18160f4168c72bc0ee5c..5b4ad58ffe9ef0cc8298d78cfde558407fa8e349 100644
--- a/ios/chrome/app/strings/ios_strings.grd
+++ b/ios/chrome/app/strings/ios_strings.grd
@@ -885,6 +885,9 @@ Handoff must also be enabled in the General section of Settings, and your device
       <message name="IDS_IOS_OPTIONS_IMPORT_DATA_KEEP_TITLE" desc="The title of the Keep Data Separate option on the Import Data settings screen. [60em]">
         Keep my data separate
       </message>
+      <message name="IDS_IOS_OPTIONS_IMPORT_DATA_TITLE_SWITCH" desc="The title of the Import Data settings screen when switching accounts. [30em]">
+        Switch Sync Account
+      </message>
       <message name="IDS_IOS_OPTIONS_PRELOAD_WEBPAGES" desc="Title for opening the setting for if/when to preload webpages. [Length: 20em] [iOS only]">
         Preload Webpages
       </message>