Add a fake cursor (blinking UIView) to the widget extension.

ios/chrome/widget_extension/widget_view.mm

Index: ios/chrome/widget_extension/widget_view.mm
diff --git a/ios/chrome/widget_extension/widget_view.mm b/ios/chrome/widget_extension/widget_view.mm
index 843adccd36fe5b34934dab71aa87cc878f48b023..d2c5a77ea27efe1d1bc675171590c3c510784604 100644
--- a/ios/chrome/widget_extension/widget_view.mm
+++ b/ios/chrome/widget_extension/widget_view.mm
@@ -8,13 +8,59 @@
 #error "This file requires ARC support."
 #endif
 
+namespace {
+
+const CGFloat kCursorHeight = 40;
+const CGFloat kCursorWidth = 2;
+const CGFloat kCursorHorizontalPadding = 40;
+
+}  // namespace
+
+@interface WidgetView ()
+
+@property(nonatomic, weak) UIView* cursor;
+
+// Creates a cursor, adds it to the view and sets the class cursor property.
+- (void)addCursor;
+
+@end
+
 @implementation WidgetView
 
-#pragma mark - Lifecycle
+@synthesize cursor = _cursor;
 
 - (instancetype)init {
   self = [super initWithFrame:CGRectZero];
+  if (self) {
+    [self addCursor];
+  }
   return self;
 }
 
+- (void)addCursor {
+  UIView* cursor = [[UIView alloc] initWithFrame:CGRectZero];
+  self.cursor = cursor;
+  self.cursor.backgroundColor = [UIColor blueColor];
+  [self addSubview:self.cursor];
+
+  [self.cursor setTranslatesAutoresizingMaskIntoConstraints:NO];
+  [NSLayoutConstraint activateConstraints:@[
+    [[self.cursor widthAnchor] constraintEqualToConstant:kCursorWidth],
+    [[self.cursor leadingAnchor]
+        constraintEqualToAnchor:self.leadingAnchor
+                       constant:kCursorHorizontalPadding],
+    [[self.cursor heightAnchor] constraintEqualToConstant:kCursorHeight],
+    [[self.cursor centerYAnchor] constraintEqualToAnchor:self.centerYAnchor]
+  ]];
+
+  [UIView animateWithDuration:0.3
+                        delay:0.0
+                      options:UIViewAnimationOptionRepeat |
+                              UIViewAnimationOptionAutoreverse
+                   animations:^{
+                     self.cursor.alpha = 0.0f;
+                   }
+                   completion:nil];
+}
+
 @end