[ios clean] Add placeholder for NTP bookmarks, chrome home and open tabs.

ios/clean/chrome/browser/ui/tab/tab_coordinator.mm

 // Copyright 2016 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/clean/chrome/browser/ui/tab/tab_coordinator.h"
 
 #include <memory>
 
 #include "base/mac/foundation_util.h"
 #include "base/memory/ptr_util.h"
@@ skipping 14 matching lines @@
 
 namespace {
 // Placeholder "experiment" flag. Change this to YES to have the toolbar at the
 // bottom.
 const BOOL kUseBottomToolbar = NO;
 }  // namespace
 
 @interface TabCoordinator ()<CRWWebStateObserver,
                              UIViewControllerTransitioningDelegate>
 @property(nonatomic, strong) TabContainerViewController* viewController;
+@property(nonatomic, weak) NTPCoordinator* ntpCoordinator;
+@property(nonatomic, weak) WebCoordinator* webCoordinator;
 @end
 
 @implementation TabCoordinator {
   std::unique_ptr<web::WebStateObserverBridge> _webStateObserver;
 }
 
 @synthesize presentationKey = _presentationKey;
 @synthesize viewController = _viewController;
 @synthesize webState = _webState;
+@synthesize webCoordinator = _webCoordinator;
+@synthesize ntpCoordinator = _ntpCoordinator;
 
 #pragma mark - BrowserCoordinator
 
 - (void)start {
   self.viewController = [self newTabContainer];
   self.viewController.transitioningDelegate = self;
   self.viewController.modalPresentationStyle = UIModalPresentationCustom;
   _webStateObserver =
       base::MakeUnique<web::WebStateObserverBridge>(self.webState, self);
 
   WebCoordinator* webCoordinator = [[WebCoordinator alloc] init];
   webCoordinator.webState = self.webState;
   [self addChildCoordinator:webCoordinator];
   // Unset the base view controller, so |webCoordinator| doesn't present its
   // view controller.
   webCoordinator.context.baseViewController = nil;
   [webCoordinator start];
+  self.webCoordinator = webCoordinator;
 
   ToolbarCoordinator* toolbarCoordinator = [[ToolbarCoordinator alloc] init];
   toolbarCoordinator.webState = self.webState;
   [self addChildCoordinator:toolbarCoordinator];
   // Unset the base view controller, so |toolbarCoordinator| doesn't present
   // its view controller.
   toolbarCoordinator.context.baseViewController = nil;
   [toolbarCoordinator start];
 
   TabStripCoordinator* tabStripCoordinator = [[TabStripCoordinator alloc] init];
   [self addChildCoordinator:tabStripCoordinator];
   // Unset the base view controller since this is a contained view controller.
   tabStripCoordinator.context.baseViewController = nil;
   [tabStripCoordinator start];
 
+  // PLACEHOLDER: Fix the order of events here. The ntpCoordinator was already
+  // created above when |webCoordinator.webState = self.webState;| triggers
+  // a load event, but then the webCoordinator stomps on the
+  // contentViewController when it starts afterwards.

[lpromero, 2017/04/06 13:01:06]

Should we then delay starting the webCoordinator then, instead of resetting the
NTP view controller?

[justincohen, 2017/04/06 18:25:11]

Perhaps, saving for a followup.

+  if (self.webState->GetLastCommittedURL() == GURL("chrome://newtab/")) {
+    self.viewController.contentViewController =
+        self.ntpCoordinator.viewController;
+  }
+
   [self.context.baseViewController presentViewController:self.viewController
                                                 animated:self.context.animated
                                               completion:nil];
+
   [super start];
 }
 
 - (void)stop {
   [super stop];
   // PLACEHOLDER: Stop child coordinators here for now. We might deal with this
   // differently later on.
   for (BrowserCoordinator* child in self.children) {
     [child stop];
   }
+
+  [self.viewController setContentViewController:nil];

[lpromero, 2017/04/06 13:01:06]

Use self.viewController.contentViewController = nil to keep the style
consistent.

[lpromero, 2017/04/06 13:01:06]

Why this call? Seems like you expect a side effect? It should be documented.
I think you should rather implement childCoordinatorWillStop and based on the
type of the coordinator, reset the content view controller. (Or maybe not even
care about the stopped child type and reset the contentViewController.)

[justincohen, 2017/04/06 18:25:11]

Done.

[justincohen, 2017/04/06 18:25:11]

Moved to childCoordinatorWillStop

+
   [self.viewController.presentingViewController
       dismissViewControllerAnimated:self.context.animated
                          completion:nil];
   _webStateObserver.reset();
 }
 
 - (void)childCoordinatorDidStart:(BrowserCoordinator*)coordinator {
   if ([coordinator isKindOfClass:[ToolbarCoordinator class]]) {
     self.viewController.toolbarViewController = coordinator.viewController;
   } else if ([coordinator isKindOfClass:[WebCoordinator class]]) {
     self.viewController.contentViewController = coordinator.viewController;
   } else if ([coordinator isKindOfClass:[TabStripCoordinator class]]) {
     self.viewController.tabStripViewController = coordinator.viewController;
+  } else if ([coordinator isKindOfClass:[NTPCoordinator class]]) {
+    self.viewController.contentViewController = coordinator.viewController;
   }
 }
 
 - (BOOL)canAddOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator {
   // This coordinator will always accept overlay coordinators.
   return YES;
 }
 
 #pragma mark - Experiment support
 
@@ skipping 10 matching lines @@
 #pragma mark - CRWWebStateObserver
 
 // This will eventually be called in -didFinishNavigation and perhaps as an
 // optimization in some equivalent to loadURL.
 - (void)webState:(web::WebState*)webState
     didCommitNavigationWithDetails:(const web::LoadCommittedDetails&)details {
   if (webState->GetLastCommittedURL() == GURL("chrome://newtab/")) {
     NTPCoordinator* ntpCoordinator = [[NTPCoordinator alloc] init];
     [self addChildCoordinator:ntpCoordinator];
     ntpCoordinator.context.baseViewController = nil;
+    ntpCoordinator.webState = self.webState;
     [ntpCoordinator start];
-    self.viewController.contentViewController = ntpCoordinator.viewController;
+    self.ntpCoordinator = ntpCoordinator;
   }
 }
 
+- (void)webState:(web::WebState*)webState
+    didStartProvisionalNavigationForURL:(const GURL&)URL {
+  if (self.ntpCoordinator) {
+    [self.ntpCoordinator stop];
+    [self removeChildCoordinator:self.ntpCoordinator];
+    self.viewController.contentViewController =
+        self.webCoordinator.viewController;
+  }
+}
+
 #pragma mark - UIViewControllerTransitioningDelegate
 
 - (id<UIViewControllerAnimatedTransitioning>)
 animationControllerForPresentedController:(UIViewController*)presented
                      presentingController:(UIViewController*)presenting
                          sourceController:(UIViewController*)source {
   ZoomTransitionAnimator* animator = [[ZoomTransitionAnimator alloc] init];
   animator.presenting = YES;
   animator.presentationKey = self.presentationKey;
   [animator selectDelegate:@[ source, presenting ]];
   return animator;
 }
 
 - (id<UIViewControllerAnimatedTransitioning>)
 animationControllerForDismissedController:(UIViewController*)dismissed {
   ZoomTransitionAnimator* animator = [[ZoomTransitionAnimator alloc] init];
   animator.presenting = NO;
   animator.presentationKey = self.presentationKey;
   [animator selectDelegate:@[ dismissed.presentingViewController ]];
   return animator;
 }
 
 @end