[ios] Active web state observer in tab collection.

ios/clean/chrome/browser/ui/tab_collection/tab_collection_mediator.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/clean/chrome/browser/ui/tab_collection/tab_collection_mediator.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/scoped_observer.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/chrome/browser/web_state_list/web_state_list.h"
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_consumer.h"
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_item.h"
 #include "ios/web/public/web_state/web_state.h"
+#import "ios/web/public/web_state/web_state_observer_bridge.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
+@interface TabCollectionMediator ()<CRWWebStateObserver>

[sczs, 2017/05/26 16:12:52]

Could we also move the WebstateListObserverving to the implementation file for
consistency? 

[edchin, 2017/05/26 18:09:00]

WSLO is needed by the subclasses so it is exposed. 

[sczs, 2017/05/30 02:32:02]

Acknowledged.

+@end
+
 @implementation TabCollectionMediator {
   std::unique_ptr<WebStateListObserverBridge> _webStateListObserver;
   std::unique_ptr<ScopedObserver<WebStateList, WebStateListObserverBridge>>
       _scopedWebStateListObserver;
+  std::unique_ptr<web::WebStateObserverBridge> _webStateObserver;
 }
 
 @synthesize webStateList = _webStateList;
 @synthesize consumer = _consumer;
 
 - (instancetype)init {
   self = [super init];
   if (self) {
     _webStateListObserver = base::MakeUnique<WebStateListObserverBridge>(self);
     _scopedWebStateListObserver = base::MakeUnique<
         ScopedObserver<WebStateList, WebStateListObserverBridge>>(
         _webStateListObserver.get());
   }
   return self;
 }
 
 - (void)dealloc {
   [self disconnect];
 }
 
 #pragma mark - Public
 
 - (void)disconnect {
   self.webStateList = nullptr;
+  _webStateObserver.reset();
 }
 
 #pragma mark - Properties
 
 - (void)setWebStateList:(WebStateList*)webStateList {
   _scopedWebStateListObserver->RemoveAll();
   _webStateList = webStateList;
   [self populateConsumerItems];
   if (_webStateList) {
     _scopedWebStateListObserver->Add(_webStateList);
@@ skipping 40 matching lines @@
   [self.consumer deleteItemAtIndex:index];
 }
 
 - (void)webStateList:(WebStateList*)webStateList
     didChangeActiveWebState:(web::WebState*)newWebState
                 oldWebState:(web::WebState*)oldWebState
                     atIndex:(int)atIndex
                  userAction:(BOOL)userAction {
   DCHECK(self.consumer);
   [self.consumer selectItemAtIndex:atIndex];
+  _webStateObserver =
+      base::MakeUnique<web::WebStateObserverBridge>(newWebState, self);
+}
+
+#pragma mark - CRWWebStateObserver
+
+- (void)webState:(web::WebState*)webState didLoadPageWithSuccess:(BOOL)success {

[rohitrao (ping after 24h), 2017/05/26 12:44:01]

Please add a comment explaining why we listen for page load notifications.  Are
we doing this to update the page title?  Or to update the snapshot?

[edchin, 2017/05/26 18:09:00]

Done.

+  int index = self.webStateList->GetIndexOfWebState(webState);
+  [self.consumer
+      replaceItemAtIndex:index
+                withItem:[self tabCollectionItemFromWebState:webState]];
 }
 
 #pragma mark - Private
 
 - (TabCollectionItem*)tabCollectionItemFromWebState:
     (const web::WebState*)webState {
   // PLACEHOLDER: Use real webstate title in the future.
   DCHECK(webState);
   GURL url = webState->GetVisibleURL();
   NSString* urlText = @"<New Tab>";
@@ skipping 16 matching lines @@
                                                         i)]];
   }
   return [items copy];
 }
 
 - (void)populateConsumerItems {
   if (self.consumer && self.webStateList) {
     [self.consumer populateItems:[self tabCollectionItemsFromWebStateList:
                                            self.webStateList]];
     [self.consumer selectItemAtIndex:self.webStateList->active_index()];
+    web::WebState* webState = self.webStateList->GetActiveWebState();
+    _webStateObserver =
+        base::MakeUnique<web::WebStateObserverBridge>(webState, self);
   }
 }
 
 @end