Convert main NTP panel to UIViewController.

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

Index: ios/chrome/browser/ui/ntp/new_tab_page_controller.mm
diff --git a/ios/chrome/browser/ui/ntp/new_tab_page_controller.mm b/ios/chrome/browser/ui/ntp/new_tab_page_controller.mm
index ec65f615c8b837fb8ab11f21d5b4546ceeee4546..358c6ffcd0ee512333ac50323f0372d212dcf774 100644
--- a/ios/chrome/browser/ui/ntp/new_tab_page_controller.mm
+++ b/ios/chrome/browser/ui/ntp/new_tab_page_controller.mm
@@ -164,6 +164,7 @@ enum {
 
 @synthesize ntpView = newTabPageView_;
 @synthesize swipeRecognizerProvider = swipeRecognizerProvider_;
+@synthesize parentViewController = parentViewController_;
 
 - (id)initWithUrl:(const GURL&)url
                 loader:(id<UrlLoader>)loader
@@ -278,6 +279,11 @@ enum {
   // 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];

[rohitrao (ping after 24h), 2017/04/12 12:45:09]

Why is this not covered by the willBeDismissed code below?

[justincohen, 2017/04/12 14:23:12]

-willMoveToParentViewController is called before the view is removed.

-removeFromParentViewController is called after the view is removed.

+
   [googleLandingController_ setDelegate:nil];
   [bookmarkController_ setDelegate:nil];
   [openTabsController_ setDelegate:nil];
@@ -287,9 +293,11 @@ enum {
 
 #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 {
+  // TODO(crbug.com/708319): Also call -willMoveToParentViewController:nil for
+  // bookmarks, open tabs and incognito here.
+  [googleLandingController_ willMoveToParentViewController:nil];
+}
 
 - (void)reload {
   [currentController_ reload];
@@ -498,6 +506,7 @@ enum {
                                       colorCache:dominantColorCache_] retain]);
     }
     view = [bookmarkController_ view];
+    // TODO(crbug.com/708319): Also addChildViewController for bookmarks here.
     [bookmarkController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kMostVisitedPanel) {
     if (!googleLandingController_) {
@@ -508,6 +517,7 @@ enum {
           webToolbarDelegate:webToolbarDelegate_
                     tabModel:tabModel_]);
     }
+    [self.parentViewController addChildViewController:googleLandingController_];
     view = [googleLandingController_ view];
     [googleLandingController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kOpenTabsPanel) {
@@ -515,6 +525,7 @@ enum {
       openTabsController_.reset([[RecentTabsPanelController alloc]
           initWithLoader:loader_
             browserState:browserState_]);
+    // TODO(crbug.com/708319): Also addChildViewController for opentabs here.
     view = [openTabsController_ view];
     [openTabsController_ setDelegate:self];
   } else if (item.identifier == NewTabPage::kIncognitoPanel) {
@@ -523,6 +534,7 @@ enum {
               initWithLoader:loader_
                 browserState:browserState_
           webToolbarDelegate:webToolbarDelegate_]);
+    // TODO(crbug.com/708319): Also addChildViewController for incognito here.
     view = [incognitoController_ view];
   } else {
     NOTREACHED();
@@ -536,6 +548,13 @@ enum {
     view.frame = [self.ntpView panelFrameForItemAtIndex:index];
     item.view = view;
     [self.ntpView.scrollView addSubview:view];
+
+    // Also didMoveToParentViewController for bookmarks, open tabs and incognito
+    // here.
+    if (item.identifier == NewTabPage::kMostVisitedPanel) {
+      [googleLandingController_
+          didMoveToParentViewController:self.parentViewController];
+    }
   }
   return created;
 }