[iOS] Fix the bug with suggestion scrolling.

Fixes a bug that would close the popup when the suggestions are scrolled
up or down.

scroll the suggestion list. The keyboard should get dismissed on iPhone,
but the suggestion list should stay on screen until "cancel" is pressed.

Bug: 1039228
Test: On any page (and NTP), focus the omnibox and type something. Now
Change-Id: Ie174223e2b963a14eea9fb31ea8ecd8243bbee3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2081415
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@{#746030}

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

@@ -139,6 +139,7 @@
 
 - (void)endEditing {
   [self.textField resignFirstResponder];
+  _editView->EndEditing();
 }
 
 - (void)insertTextToOmnibox:(NSString*)text {

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

@@ -221,15 +221,13 @@ const CGFloat kClearButtonSize = 28.0f;
   return YES;
 }
 
-// When editing, forward the message on to |_textChangeDelegate|.
+// Record the metrics as needed.
 - (void)textFieldDidEndEditing:(UITextField*)textField
                         reason:(UITextFieldDidEndEditingReason)reason {
   if (!self.omniboxInteractedWhileFocused) {
     RecordAction(
         UserMetricsAction("Mobile_FocusedDefocusedOmnibox_WithNoAction"));
   }
-  DCHECK(_textChangeDelegate);
-  _textChangeDelegate->EndEditing();
 }
 
 - (BOOL)textFieldShouldClear:(UITextField*)textField {