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

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

Index: ios/clean/chrome/browser/ui/tab/tab_coordinator.mm
diff --git a/ios/clean/chrome/browser/ui/tab/tab_coordinator.mm b/ios/clean/chrome/browser/ui/tab/tab_coordinator.mm
index 59497cb2e159e0165b1fa94e3b025c0ca8759c21..e96fac04c9e050c5bba7e7e33f9d0b34f4731e3d 100644
--- a/ios/clean/chrome/browser/ui/tab/tab_coordinator.mm
+++ b/ios/clean/chrome/browser/ui/tab/tab_coordinator.mm
@@ -32,6 +32,8 @@ const BOOL kUseBottomToolbar = NO;
 @interface TabCoordinator ()<CRWWebStateObserver,
                              UIViewControllerTransitioningDelegate>
 @property(nonatomic, strong) TabContainerViewController* viewController;
+@property(nonatomic, weak) NTPCoordinator* ntpCoordinator;
+@property(nonatomic, weak) WebCoordinator* webCoordinator;
 @end
 
 @implementation TabCoordinator {
@@ -41,6 +43,8 @@ const BOOL kUseBottomToolbar = NO;
 @synthesize presentationKey = _presentationKey;
 @synthesize viewController = _viewController;
 @synthesize webState = _webState;
+@synthesize webCoordinator = _webCoordinator;
+@synthesize ntpCoordinator = _ntpCoordinator;
 
 #pragma mark - BrowserCoordinator
 
@@ -58,6 +62,7 @@ const BOOL kUseBottomToolbar = NO;
   // view controller.
   webCoordinator.context.baseViewController = nil;
   [webCoordinator start];
+  self.webCoordinator = webCoordinator;
 
   ToolbarCoordinator* toolbarCoordinator = [[ToolbarCoordinator alloc] init];
   toolbarCoordinator.webState = self.webState;
@@ -73,9 +78,19 @@ const BOOL kUseBottomToolbar = NO;
   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];
 }
 
@@ -86,6 +101,9 @@ const BOOL kUseBottomToolbar = NO;
   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];
@@ -99,6 +117,8 @@ const BOOL kUseBottomToolbar = NO;
     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;
   }
 }
 
@@ -129,8 +149,19 @@ const BOOL kUseBottomToolbar = NO;
     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;
   }
 }