Adding search widget UI and functionality.

ios/chrome/search_widget_extension/search_widget_view_controller.mm

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/search_widget_extension/search_widget_view_controller.h"
 
 #import <NotificationCenter/NotificationCenter.h>
 
 #include "base/ios/ios_util.h"
 #include "base/mac/foundation_util.h"
@@ skipping 50 matching lines @@
                  delegate:nil];
   }
   return self;
 }
 
 #pragma mark - UIViewController
 
 - (void)viewDidLoad {
   [super viewDidLoad];
 
+  UIVibrancyEffect* primary;
+  UIVibrancyEffect* secondary;
+  if (base::ios::IsRunningOnIOS10OrLater()) {
+    primary = [UIVibrancyEffect widgetPrimaryVibrancyEffect];
+    secondary = [UIVibrancyEffect widgetSecondaryVibrancyEffect];
+  } else {
+    primary = [UIVibrancyEffect notificationCenterVibrancyEffect];
+    secondary = [UIVibrancyEffect notificationCenterVibrancyEffect];
+  }
+
   // A local variable is necessary here as the property is declared weak and the
   // object would be deallocated before being retained by the addSubview call.
   SearchWidgetView* widgetView =
-      [[SearchWidgetView alloc] initWithActionTarget:self];
+      [[SearchWidgetView alloc] initWithActionTarget:self
+                               primaryVibrancyEffect:primary
+                             secondaryVibrancyEffect:secondary];
   self.widgetView = widgetView;
   [self.view addSubview:self.widgetView];
 
   if (base::ios::IsRunningOnIOS10OrLater()) {
     self.extensionContext.widgetLargestAvailableDisplayMode =
         NCWidgetDisplayModeExpanded;
   }
 
   self.widgetView.translatesAutoresizingMaskIntoConstraints = NO;
 
-  NSLayoutConstraint* heightAnchor = [self.widgetView.heightAnchor
-      constraintEqualToAnchor:self.view.heightAnchor];
-  heightAnchor.priority = 900;
-
   [NSLayoutConstraint activateConstraints:@[

[stkhapugin, 2017/05/04 13:12:09]

I think you can replace this code with a helper that pins all 4 sides of a view
to another view. Forgot what it's called though. 

[lody, 2017/05/05 17:05:44]

Done.

     [self.widgetView.leadingAnchor
         constraintEqualToAnchor:self.view.leadingAnchor],
-    [self.widgetView.widthAnchor constraintEqualToAnchor:self.view.widthAnchor],
     [self.widgetView.trailingAnchor
         constraintEqualToAnchor:self.view.trailingAnchor],
-    heightAnchor,
+    [self.widgetView.bottomAnchor
+        constraintEqualToAnchor:self.view.bottomAnchor],
     [self.widgetView.topAnchor constraintEqualToAnchor:self.view.topAnchor],
   ]];
 }
 
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
   [self updateWidget];
 }
 
 - (void)widgetPerformUpdateWithCompletionHandler:
@@ skipping 10 matching lines @@
     [self.widgetView updateCopiedURL:self.copiedURL.absoluteString];
     return YES;
   }
   return NO;
 }
 
 #pragma mark - NCWidgetProviding
 
 - (void)widgetActiveDisplayModeDidChange:(NCWidgetDisplayMode)activeDisplayMode
                          withMaximumSize:(CGSize)maxSize {
+  // Set the copied URL section here so that the fitting size is correctly
+  // calculated.
+  [self.widgetView
+      setCopiedURLVisible:(activeDisplayMode == NCWidgetDisplayModeExpanded)];
   CGSize fittingSize = [self.widgetView

[stkhapugin, 2017/05/04 13:12:09]

Please add a newline and a comment for line 138 and below

[lody, 2017/05/05 17:05:44]

Done.

       systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
   if (fittingSize.height > maxSize.height) {
     self.preferredContentSize = maxSize;
   } else {
     self.preferredContentSize = fittingSize;
   }
 }
 
 #pragma mark - WidgetViewActionTarget
 
@@ skipping 78 matching lines @@
     };
   }
   return @{
     timePrefKey : [NSDate date],
     appPrefKey : @"TodayExtension",
     commandPrefKey : command,
   };
 }
 
 @end