[multiball] Fix omnibox focus bugs.

The omnibox' textfield is focused programmatically upon a button press.
This is no longer as straightforward as it was in single window. On iOS
13, tapping a textfield will make the corresponding window key if
necessary. Do this before becoming first responder.

Bug: 1072414, 1092824
Change-Id: I9b9df1d41c84a89f820c813f8fa2691897dc6076
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2312704
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Robbie Gibson <rkgibson@google.com>
Cr-Commit-Position: refs/heads/master@{#791242}

ios/chrome/browser/ui/omnibox/BUILD.gn

@@ -160,6 +160,7 @@ source_set("omnibox_internal") {
     "//ios/chrome/browser/ui/toolbar/public",
     "//ios/chrome/browser/ui/toolbar/public:feature_flags",
     "//ios/chrome/browser/ui/util",
+    "//ios/chrome/browser/ui/util:multiwindow_util",
     "//ios/chrome/common",
     "//ios/chrome/common/ui/colors",
     "//ios/chrome/common/ui/favicon",

ios/chrome/browser/ui/omnibox/omnibox_coordinator.mm

@@ -29,6 +29,7 @@
 #import "ios/chrome/browser/ui/omnibox/popup/omnibox_popup_coordinator.h"
 #include "ios/chrome/browser/ui/omnibox/popup/omnibox_popup_view_ios.h"
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
+#import "ios/chrome/browser/ui/util/multi_window_support.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -128,6 +129,16 @@
 - (void)focusOmnibox {
   if (![self.textField isFirstResponder]) {
     base::RecordAction(base::UserMetricsAction("MobileOmniboxFocused"));
+
+    // In multiwindow context, -becomeFirstRepsonder is not enough to get the
+    // keyboard input. The window will not automatically become key. Make it key
+    // manually. UITextField does this under the hood when tapped from
+    // -[UITextInteractionAssistant(UITextInteractionAssistant_Internal)
+    // setFirstResponderIfNecessaryActivatingSelection:]
+    if (IsMultiwindowSupported()) {
+      [self.textField.window makeKeyAndVisible];
+    }
+
     [self.textField becomeFirstResponder];
   }
 }