[iOS] Don't hide the omnibox on incognito NTP

The omnibox should only be hidden on non-incognito NTP.

Fixed: 1090521
Change-Id: I521a466b92eb29ccbef78e90b4c6e02aedff091c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2236410
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: David Jean <djean@chromium.org>
Reviewed-by: David Jean <djean@chromium.org>
Auto-Submit: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#777303}

ios/chrome/browser/ui/toolbar/primary_toolbar_coordinator.mm

@@ -11,6 +11,7 @@
 #include "base/mac/foundation_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/sys_string_conversions.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #import "ios/chrome/browser/main/browser.h"
 #import "ios/chrome/browser/ui/commands/command_dispatcher.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_controller.h"
@@ -71,6 +72,8 @@
                    forProtocol:@protocol(FakeboxFocuser)];
 
   self.viewController = [[PrimaryToolbarViewController alloc] init];
+  self.viewController.shouldHideOmniboxOnNTP =
+      !self.browser->GetBrowserState()->IsOffTheRecord();
   self.viewController.buttonFactory = [self buttonFactoryWithType:PRIMARY];
   // TODO(crbug.com/1045047): Use HandlerForProtocol after commands protocol
   // clean up.

ios/chrome/browser/ui/toolbar/primary_toolbar_view_controller.h

@@ -21,6 +21,9 @@
 
 @property(nonatomic, weak) id<PrimaryToolbarViewControllerDelegate> delegate;
 
+// Whether the omnibox should be hidden on NTP.
+@property(nonatomic, assign) BOOL shouldHideOmniboxOnNTP;
+
 // Sets the location bar view controller, containing the omnibox.
 - (void)setLocationBarViewController:(UIViewController*)locationBarView;
 

ios/chrome/browser/ui/toolbar/primary_toolbar_view_controller.mm

@@ -164,10 +164,16 @@
     return;
   [super setIsNTP:isNTP];
   _isNTP = isNTP;
-  if (!isNTP && !IsSplitToolbarMode(self)) {
+  if (IsSplitToolbarMode(self) || !self.shouldHideOmniboxOnNTP)
+    return;
+
+  // This is hiding/showing and positionning the omnibox. This is only needed
+  // if the omnibox should be hidden when there is only one toolbar.
+  if (!isNTP) {
     // Reset any location bar view updates when not an NTP.
     [self setScrollProgressForTabletOmnibox:1];
-  } else if (isNTP && !IsSplitToolbarMode(self)) {
+  } else {
+    // Hides the omnibox.
     [self setScrollProgressForTabletOmnibox:0];
   }
 }