Remove FirstResponderKeyWindow flag.

Disabling this feature is no longer a valid working state as it breaks
the autofill keyboard accessory.

Bug: None
Change-Id: Ic5bb57e420567c690aff36245cb47b2c508a15e0
Reviewed-on: https://chromium-review.googlesource.com/c/1305239
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611221}

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -4,9 +4,6 @@
 
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
 
-const base::Feature kFirstResponderKeyWindow{"FirstResponderKeyWindow",
-                                             base::FEATURE_ENABLED_BY_DEFAULT};
-
 // TODO(crbug.com/893314) : Remove this flag.
 const base::Feature kClosingLastIncognitoTab{"ClosingLastIncognitoTab",
                                              base::FEATURE_ENABLED_BY_DEFAULT};

ios/chrome/browser/ui/ui_feature_flags.h

@@ -7,11 +7,6 @@
 
 #include "base/feature_list.h"
 
-// Avoid the crash in https://crbug.com/816427 by getting the first responder by
-// navigating the key window, rather than using -sendAction to find the first
-// responder.
-extern const base::Feature kFirstResponderKeyWindow;
-
 // Feature to automatically switch to the regular tabs panel in tab grid after
 // closing the last incognito tab.
 extern const base::Feature kClosingLastIncognitoTab;

ios/chrome/browser/ui/util/uikit_ui_util.mm

@@ -65,19 +65,8 @@ void GetRGBA(UIColor* color, CGFloat* r, CGFloat* g, CGFloat* b, CGFloat* a) {
   }
 }
 
-// Store a reference to the current first responder.
-UIResponder* gFirstResponder = nil;
-
 }  // namespace
 
-@implementation UIResponder (FirstResponder)
-
-- (void)cr_markSelfCurrentFirstResponder {
-  gFirstResponder = self;
-}
-
-@end
-
 void SetA11yLabelAndUiAutomationName(UIView* element,
                                      int idsAccessibilityLabel,
                                      NSString* englishUiAutomationName) {
@@ -642,19 +631,7 @@ UIView* GetFirstResponderSubview(UIView* view) {
 
 UIResponder* GetFirstResponder() {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
-  UIApplication* application = [UIApplication sharedApplication];
-  if (base::FeatureList::IsEnabled(kFirstResponderKeyWindow)) {
-    return GetFirstResponderSubview(application.keyWindow);
-  }
-
-  DCHECK(!gFirstResponder);
-  [application sendAction:@selector(cr_markSelfCurrentFirstResponder)
-                       to:nil
-                     from:nil
-                 forEvent:nil];
-  UIResponder* firstResponder = gFirstResponder;
-  gFirstResponder = nil;
-  return firstResponder;
+  return GetFirstResponderSubview([UIApplication sharedApplication].keyWindow);
 }
 
 // Trigger a haptic vibration for the user selecting an action. This is a no-op