Do not use GetFirstResponderSubview on iOS 10.

When a WKWebView is displaying a PDF, the first responder is not in the view hierarchy (but a class adhering to UIResponder).

Bug: 882470
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I6f9e993e740541b7cf009b1d11e16183b409fdae
Reviewed-on: https://chromium-review.googlesource.com/c/1284438
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600620}

ios/chrome/browser/autofill/form_suggestion_controller_unittest.mm

@@ -21,6 +21,7 @@
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/web/public/navigation_manager.h"
 #import "ios/web/public/test/fakes/test_web_state.h"
+#include "ios/web/public/test/test_web_thread_bundle.h"
 #import "ios/web/public/web_state/ui/crw_web_view_proxy.h"
 #import "ios/web/public/web_state/web_state.h"
 #import "testing/gtest_mac.h"
@@ -235,6 +236,9 @@ class FormSuggestionControllerTest : public PlatformTest {
   // Accessory view controller.
   FormInputAccessoryMediator* accessory_mediator_;
 
+  // The associated test Web Threads.
+  web::TestWebThreadBundle thread_bundle_;
+
   // The fake WebState to simulate navigation and JavaScript events.
   web::TestWebState test_web_state_;
 

ios/chrome/browser/ui/uikit_ui_util.mm

@@ -12,6 +12,7 @@
 #import <UIKit/UIKit.h>
 #include <cmath>
 
+#include "base/ios/ios_util.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #include "base/numerics/math_constants.h"
@@ -600,19 +601,21 @@ UIView* GetFirstResponderSubview(UIView* view) {
 }
 
 UIResponder* GetFirstResponder() {
-  if (!base::FeatureList::IsEnabled(kFirstResponderKeyWindow)) {
-    DCHECK_CURRENTLY_ON(web::WebThread::UI);
-    DCHECK(!gFirstResponder);
-    [[UIApplication sharedApplication]
-        sendAction:@selector(cr_markSelfCurrentFirstResponder)
-                to:nil
-              from:nil
-          forEvent:nil];
-    UIResponder* firstResponder = gFirstResponder;
-    gFirstResponder = nil;
-    return firstResponder;
+  UIApplication* application = [UIApplication sharedApplication];
+  if (base::ios::IsRunningOnIOS11OrLater() &&
+      base::FeatureList::IsEnabled(kFirstResponderKeyWindow)) {
+    return GetFirstResponderSubview(application.keyWindow);
   }
-  return GetFirstResponderSubview([UIApplication sharedApplication].keyWindow);
+
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  DCHECK(!gFirstResponder);
+  [application sendAction:@selector(cr_markSelfCurrentFirstResponder)
+                       to:nil
+                     from:nil
+                 forEvent:nil];
+  UIResponder* firstResponder = gFirstResponder;
+  gFirstResponder = nil;
+  return firstResponder;
 }
 
 // Trigger a haptic vibration for the user selecting an action. This is a no-op