[ios] Anchors the locationBarStackView bottom to the toolbar

Since the locationBarContainer is expanded and its stackView is not, this CL creates a margin
constant and anchors the bottomAnchor to the toolbar bottomAnchor, this way the Y position of the
StackView is not changed during expansion or contraction.

Bug: 796482
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I69aac20beb0a2b3b31d516b78da7b1b4ba3a6ab8
Reviewed-on: https://chromium-review.googlesource.com/841442Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526016}

ios/chrome/browser/ui/toolbar/clean/toolbar_constants.h

@@ -35,6 +35,9 @@ extern const CGFloat kLocationBarShadowHeight;
 extern const CGFloat kLocationBarShadowInset;
 extern const CGFloat kIcongnitoLocationBackgroundColor;
 
+// Location bar StackView constraints.
+extern const CGFloat klocationBarStackViewBottomMargin;
+
 // Progress Bar Height.
 extern const CGFloat kProgressBarHeight;
 

ios/chrome/browser/ui/toolbar/clean/toolbar_constants.mm

@@ -25,6 +25,8 @@ const CGFloat kLocationBarShadowHeight = 2.0f;
 const CGFloat kLocationBarShadowInset = 1.0f;
 const CGFloat kIcongnitoLocationBackgroundColor = 0x737373;
 
+const CGFloat klocationBarStackViewBottomMargin = 8.0f;
+
 const CGFloat kProgressBarHeight = 2.0f;
 
 const CGFloat kToolsMenuButtonWidth = 44.0f;

ios/chrome/browser/ui/toolbar/clean/toolbar_view_controller.mm

@@ -572,22 +572,18 @@
   // LocationBarContainer View.
   UILayoutGuide* locationBarContainerSafeAreaGuide =
       SafeAreaLayoutGuideForView(self.locationBarContainer);
-  NSLayoutConstraint* locationBarContainerStackViewTopConstraint =
-      [self.locationBarContainerStackView.topAnchor
-          constraintEqualToAnchor:self.locationBarContainer.topAnchor];
   [NSLayoutConstraint activateConstraints:@[
     [self.locationBarContainerStackView.bottomAnchor
-        constraintEqualToAnchor:self.locationBarContainer.bottomAnchor],
+        constraintEqualToAnchor:self.view.bottomAnchor
+                       constant:-(klocationBarStackViewBottomMargin +
+                                  kLocationBarVerticalMargin)],
     [self.locationBarContainerStackView.trailingAnchor
         constraintEqualToAnchor:locationBarContainerSafeAreaGuide
                                     .trailingAnchor],
     [self.locationBarContainerStackView.leadingAnchor
         constraintEqualToAnchor:locationBarContainerSafeAreaGuide
                                     .leadingAnchor],
-    locationBarContainerStackViewTopConstraint,
   ]];
-  [self.regularToolbarConstraints
-      addObject:locationBarContainerStackViewTopConstraint];
 }
 
 #pragma mark - Components Setup
@@ -1064,9 +1060,6 @@
           constraintEqualToAnchor:self.view.leadingAnchor],
       [self.locationBarContainer.trailingAnchor
           constraintEqualToAnchor:self.view.trailingAnchor],
-      [self.locationBarContainerStackView.topAnchor
-          constraintEqualToAnchor:self.topSafeAnchor
-                         constant:kExpandedLocationBarVerticalMargin],
     ];
   }
   return _expandedToolbarConstraints;