[ios] Experimental flag for Pending Index Navigations.

ios/chrome/browser/experimental_flags.mm

Index: ios/chrome/browser/experimental_flags.mm
diff --git a/ios/chrome/browser/experimental_flags.mm b/ios/chrome/browser/experimental_flags.mm
index 4c8470815bf44797abd87237e2a8bac09eabdadc..4919bd515f725033f10e1d586a3e8413541d2258 100644
--- a/ios/chrome/browser/experimental_flags.mm
+++ b/ios/chrome/browser/experimental_flags.mm
@@ -29,6 +29,8 @@ NSString* const kHeuristicsForPasswordGeneration =
 NSString* const kEnableReadingList = @"EnableReadingList";
 NSString* const kEnableNewClearBrowsingDataUI = @"EnableNewClearBrowsingDataUI";
 NSString* const kMDMIntegrationDisabled = @"MDMIntegrationDisabled";
+NSString* const kPendingIndexNavigationEnabled =
+    @"PendingIndexNavigationEnabled";
 }  // namespace
 
 namespace experimental_flags {
@@ -180,4 +182,9 @@ bool IsMDMIntegrationEnabled() {
       boolForKey:kMDMIntegrationDisabled];
 }
 
+bool IsPendingIndexNavigationEnabled() {
+  return [[NSUserDefaults standardUserDefaults]
+      boolForKey:kPendingIndexNavigationEnabled];
+}
+
 }  // namespace experimental_flags