[iOS][MF] Make sure the gray line is hidden when appears

View was being hidden on prepare to reuse only, causing it to be shown
the first time the cell was used.

Bug: 845472, 911148
Change-Id: Ic59d5de5f476c7e499d40a244ef1291e4ccd3bfa
Reviewed-on: https://chromium-review.googlesource.com/c/1358447
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613128}

ios/chrome/browser/ui/autofill/manual_fill/action_cell.mm

@@ -89,7 +89,6 @@ static const CGFloat BottomBaseSystemSpacingMultiplier = 1.5;
   [self.titleButton setTitleColor:UIColor.cr_manualFillTintColor
                          forState:UIControlStateNormal];
   self.titleButton.enabled = YES;
-  self.grayLine.hidden = YES;
 }
 
 - (void)setUpWithTitle:(NSString*)title
@@ -101,7 +100,7 @@ static const CGFloat BottomBaseSystemSpacingMultiplier = 1.5;
     [self createView];
   }
 
-  NSMutableArray<UIView*>* verticalLeadViews = [[NSMutableArray alloc] init];
+  self.grayLine.hidden = !showSeparator;
 
   [self.titleButton setTitle:title forState:UIControlStateNormal];
   self.titleButton.accessibilityIdentifier = accessibilityID;
@@ -111,11 +110,9 @@ static const CGFloat BottomBaseSystemSpacingMultiplier = 1.5;
                            forState:UIControlStateNormal];
   }
   self.action = action;
-  [verticalLeadViews addObject:self.titleButton];
 
-  if (showSeparator) {
-    self.grayLine.hidden = NO;
-  }
+  NSMutableArray<UIView*>* verticalLeadViews = [[NSMutableArray alloc] init];
+  [verticalLeadViews addObject:self.titleButton];
 
   self.verticalConstraints =
       VerticalConstraintsSpacingForViewsInContainerWithMultipliers(