[iOS] FindInPage: Clean up iOS 12 and fix Dark Mode bug

The bug occured because the overridesUserInterfaceStyle for this was in
the view that contained FindBarViewController's view, and
overridesUserInterfaceStyle from a view doesn't propagate down to
embedded view controllers. This has probably been around since the
Dark Mode migration.

Bug: 1222388
Change-Id: If733aa2964da965df8f5e2af77b1b6d05ec8d5a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2976972
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Cr-Commit-Position: refs/heads/master@{#894656}

ios/chrome/browser/ui/find_bar/find_bar_view.h

@@ -12,10 +12,8 @@
 // in format of "1 of 13", and next/previous/close buttons.
 @interface FindBarView : UIView
 
-// Designated initializer. |darkAppearance| makes the background to dark color
-// and changes font colors to lighter colors.
-- (instancetype)initWithDarkAppearance:(BOOL)darkAppearance
-    NS_DESIGNATED_INITIALIZER;
+// Designated initializer.
+- (instancetype)init NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithFrame:(CGRect)frame NS_UNAVAILABLE;
 - (instancetype)initWithCoder:(NSCoder*)aDecoder NS_UNAVAILABLE;

ios/chrome/browser/ui/find_bar/find_bar_view.mm

@@ -37,8 +37,6 @@ const CGFloat kButtonLength = 44;
 // The overlay that shows number of results in format "1 of 13".
 @property(nonatomic, strong) UILabel* resultsCountLabel;
 
-@property(nonatomic, assign) BOOL darkMode;
-
 @end
 
 @implementation FindBarView
@@ -48,15 +46,11 @@ const CGFloat kButtonLength = 44;
 @synthesize nextButton = _nextButton;
 @synthesize closeButton = _closeButton;
 @synthesize resultsCountLabel = _resultsCountLabel;
-@synthesize darkMode = _darkMode;
 
 #pragma mark - Public
 
-- (instancetype)initWithDarkAppearance:(BOOL)darkAppearance {
+- (instancetype)init {
   self = [super initWithFrame:CGRectZero];
-  if (self) {
-    _darkMode = darkAppearance;
-  }
   return self;
 }
 
@@ -142,23 +136,16 @@ const CGFloat kButtonLength = 44;
   ]];
 }
 
-// Sets the colors for the different subviews, based on the |darkMode|.
+// Sets the colors for the different subviews.
 - (void)setupColors {
-  UIColor* inputFieldBackground = color::DarkModeDynamicColor(
-      [UIColor colorNamed:kTextfieldBackgroundColor], self.darkMode,
-      [UIColor colorNamed:kTextfieldBackgroundDarkColor]);
-  UIColor* inputFieldPlaceHolderTextColor = color::DarkModeDynamicColor(
-      [UIColor colorNamed:kTextfieldPlaceholderColor], self.darkMode,
-      [UIColor colorNamed:kTextfieldPlaceholderDarkColor]);
-  UIColor* inputFieldTextColor = color::DarkModeDynamicColor(
-      [UIColor colorNamed:kTextPrimaryColor], self.darkMode,
-      [UIColor colorNamed:kTextPrimaryDarkColor]);
-  UIColor* resultsCountLabelTextColor = color::DarkModeDynamicColor(
-      [UIColor colorNamed:kTextfieldPlaceholderColor], self.darkMode,
-      [UIColor colorNamed:kTextfieldPlaceholderDarkColor]);
-  UIColor* buttonTintColor = color::DarkModeDynamicColor(
-      [UIColor colorNamed:kBlueColor], self.darkMode,
-      [UIColor colorNamed:kBlueDarkColor]);
+  UIColor* inputFieldBackground =
+      [UIColor colorNamed:kTextfieldBackgroundColor];
+  UIColor* inputFieldPlaceHolderTextColor =
+      [UIColor colorNamed:kTextfieldPlaceholderColor];
+  UIColor* inputFieldTextColor = [UIColor colorNamed:kTextPrimaryColor];
+  UIColor* resultsCountLabelTextColor =
+      [UIColor colorNamed:kTextfieldPlaceholderColor];
+  UIColor* buttonTintColor = [UIColor colorNamed:kBlueColor];
 
   self.inputField.backgroundColor = inputFieldBackground;
   NSString* placeholder = [self.inputField placeholder];

ios/chrome/browser/ui/find_bar/find_bar_view_controller.mm

@@ -21,7 +21,9 @@
 
 - (instancetype)initWithDarkAppearance:(BOOL)darkAppearance {
   if (self = [super initWithNibName:nil bundle:nil]) {
-    _darkAppearance = darkAppearance;
+    self.overrideUserInterfaceStyle = darkAppearance
+                                          ? UIUserInterfaceStyleDark
+                                          : UIUserInterfaceStyleUnspecified;
   }
   return self;
 }
@@ -29,7 +31,7 @@
 #pragma mark - UIView
 
 - (void)loadView {
-  self.view = [[FindBarView alloc] initWithDarkAppearance:self.darkAppearance];
+  self.view = [[FindBarView alloc] init];
   self.view.translatesAutoresizingMaskIntoConstraints = NO;
 }