Convert main NTP panel to UIViewController.

ios/chrome/browser/ui/ntp/new_tab_page_controller.mm

 // Copyright 2012 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/browser/ui/ntp/new_tab_page_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #import "base/ios/weak_nsobject.h"
 #include "base/logging.h"
@@ skipping 146 matching lines @@
 // Returns the ID for the currently selected panel.
 - (NewTabPage::PanelIdentifier)selectedPanelID;
 
 @property(nonatomic, retain) NewTabPageView* ntpView;
 @end
 
 @implementation NewTabPageController
 
 @synthesize ntpView = newTabPageView_;
 @synthesize swipeRecognizerProvider = swipeRecognizerProvider_;
+@synthesize parentViewController = parentViewController_;
 
 - (id)initWithUrl:(const GURL&)url
                 loader:(id<UrlLoader>)loader
                focuser:(id<OmniboxFocuser>)focuser
            ntpObserver:(id<NewTabPageControllerObserver>)ntpObserver
           browserState:(ios::ChromeBrowserState*)browserState
             colorCache:(NSMutableDictionary*)colorCache
     webToolbarDelegate:(id<WebToolbarDelegate>)webToolbarDelegate
               tabModel:(TabModel*)tabModel {
   self = [super initWithNibName:nil url:url];
@@ skipping 94 matching lines @@
     [self showPanel:itemToDisplay];
     [self updateOverlayScrollPosition];
   }
   return self;
 }
 
 - (void)dealloc {
   // Animations can last past the life of the NTP controller, nil out the
   // delegate.
   self.ntpView.scrollView.delegate = nil;
+
+  // TODO(crbug.com/708319): Also call -removeFromParentViewController for
+  // bookmarks, open tabs and incognit here.
+  [googleLandingController_ removeFromParentViewController];
+
   [googleLandingController_ setDelegate:nil];
   [bookmarkController_ setDelegate:nil];
   [openTabsController_ setDelegate:nil];
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   [super dealloc];
 }
 
 #pragma mark - CRWNativeContent
 
-// Note: No point implementing -handleLowMemory because all native content
-// views but the selected one are dropped, and the selected view doesn't
-// need to do anything.
+- (void)willBeDismissed {

[rohitrao (ping after 24h), 2017/04/13 12:48:52]

Explain that this is called by //web immediately before this controller's view
is removed from the view hierarchy.

[justincohen, 2017/04/13 13:58:02]

Done.

+  // TODO(crbug.com/708319): Also call -willMoveToParentViewController:nil for
+  // bookmarks, open tabs and incognito here.
+  [googleLandingController_ willMoveToParentViewController:nil];
+}
 
 - (void)reload {
   [currentController_ reload];
   [super reload];
 }
 
 - (void)wasShown {
   [currentController_ wasShown];
   // Ensure that the NTP has the latest data when it is shown.
   [self reload];
@@ skipping 175 matching lines @@
 
 - (void)loadControllerWithIndex:(NSUInteger)index {
   if (index >= self.ntpView.tabBar.items.count)
     return;
 
   NewTabPageBarItem* item = [self.ntpView.tabBar.items objectAtIndex:index];
   [self loadPanel:item];
 }
 
 - (BOOL)loadPanel:(NewTabPageBarItem*)item {
-  UIView* view;
+  UIView* view = nil;
+  UIViewController* panelController = nil;
   BOOL created = NO;
   // Only load the controllers once.
   if (item.identifier == NewTabPage::kBookmarksPanel) {
     if (!bookmarkController_) {
       base::scoped_nsobject<BookmarkControllerFactory> factory(
           [[BookmarkControllerFactory alloc] init]);
       bookmarkController_.reset([[factory
           bookmarkPanelControllerForBrowserState:browserState_
                                           loader:loader_
                                       colorCache:dominantColorCache_] retain]);
     }
     view = [bookmarkController_ view];
+    // TODO(crbug.com/708319): Also set panelController for bookmarks here.
     [bookmarkController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kMostVisitedPanel) {
     if (!googleLandingController_) {
       googleLandingController_.reset([[GoogleLandingController alloc]
               initWithLoader:loader_
                 browserState:browserState_
                      focuser:focuser_
           webToolbarDelegate:webToolbarDelegate_
                     tabModel:tabModel_]);
     }
+    panelController = googleLandingController_;
     view = [googleLandingController_ view];
     [googleLandingController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kOpenTabsPanel) {
     if (!openTabsController_)
       openTabsController_.reset([[RecentTabsPanelController alloc]
           initWithLoader:loader_
             browserState:browserState_]);
+    // TODO(crbug.com/708319): Also set panelController for opentabs here.
     view = [openTabsController_ view];
     [openTabsController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kIncognitoPanel) {
     if (!incognitoController_)
       incognitoController_.reset([[IncognitoPanelController alloc]
               initWithLoader:loader_
                 browserState:browserState_
           webToolbarDelegate:webToolbarDelegate_]);
+    // TODO(crbug.com/708319): Also set panelController for incognito here.
     view = [incognitoController_ view];
   } else {
     NOTREACHED();
     return NO;
   }
 
   // Add the panel views to the scroll view in the proper location.
   NSUInteger index = [self tabBarItemIndex:item];
   if (view.superview == nil) {
     created = YES;
     view.frame = [self.ntpView panelFrameForItemAtIndex:index];
     item.view = view;
+
+    // To ease modernizing the NTP only the internal panels are being converted
+    // to UIViewControllers.  This means all the plumbing between the
+    // BrowserViewController and the internal NTP panels (WebController, NTP)
+    // hierarchy is skipped.  While normally the logic to push and pop a view
+    // controller would be owned by a coordinator, in this case the old NTP
+    // controller adds and removes child view controllers itself when a load
+    // is initiated, and when WebController calls -willBeDismissed.
+    // TODO(crbug.com/708319):This 'if' can become a DCHECK once all panels move
+    // to panelControllers.
+    if (panelController)
+      [self.parentViewController addChildViewController:panelController];
     [self.ntpView.scrollView addSubview:view];
+    if (panelController)
+      [panelController didMoveToParentViewController:self.parentViewController];
   }
   return created;
 }
 
 - (void)scrollToPanel:(NewTabPageBarItem*)item animate:(BOOL)animate {
   NSUInteger index = [self tabBarItemIndex:item];
   if (IsIPadIdiom()) {
     CGRect itemFrame = [self.ntpView panelFrameForItemAtIndex:index];
     CGPoint point = CGPointMake(CGRectGetMinX(itemFrame), 0);
     [self.ntpView.scrollView setContentOffset:point animated:animate];
@@ skipping 127 matching lines @@
 
 - (void)updateNtpBarShadowForPanelController:
     (id<NewTabPagePanelProtocol>)ntpPanelController {
   if (currentController_ != ntpPanelController)
     return;
   [self.ntpView.tabBar
       setShadowAlpha:[ntpPanelController alphaForBottomShadow]];
 }
 
 @end