Remove TabModelObserver usage from TabStripController.

The last method from didChangeTab which was used to update tab title
and update the loading spinner.
Instead of using TabModelObserver didChangeTab, use WebStateObserver to
monitor all webStates and use didStartLoading/didStopLoading to update
the spinner. Also use WebStateObserver didChangeTitle to update the
tabview title.

Bug: 911350
Change-Id: Ie1b0bfc77d7dca39e27e6efb6e8478aaaf9e9a4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1630628
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664280}

ios/chrome/browser/ui/tabs/tab_strip_controller.mm

@@ -24,7 +24,6 @@
 #import "ios/chrome/browser/tabs/legacy_tab_helper.h"
 #import "ios/chrome/browser/tabs/tab.h"
 #import "ios/chrome/browser/tabs/tab_model.h"
-#import "ios/chrome/browser/tabs/tab_model_observer.h"
 #import "ios/chrome/browser/tabs/tab_title_util.h"
 #import "ios/chrome/browser/ui/bubble/bubble_util.h"
 #import "ios/chrome/browser/ui/bubble/bubble_view.h"
@@ -44,11 +43,13 @@
 #include "ios/chrome/browser/ui/util/rtl_geometry.h"
 #include "ios/chrome/browser/ui/util/ui_util.h"
 #import "ios/chrome/browser/ui/util/uikit_ui_util.h"
+#include "ios/chrome/browser/web_state_list/all_web_state_observation_forwarder.h"
 #import "ios/chrome/browser/web_state_list/web_state_list.h"
 #import "ios/chrome/browser/web_state_list/web_state_list_favicon_driver_observer.h"
 #import "ios/chrome/browser/web_state_list/web_state_list_observer_bridge.h"
 #include "ios/chrome/grit/ios_strings.h"
 #import "ios/web/public/web_state/web_state.h"
+#import "ios/web/public/web_state/web_state_observer_bridge.h"
 #include "third_party/google_toolbox_for_mac/src/iPhone/GTMFadeTruncatingLabel.h"
 #include "ui/gfx/image/image.h"
 
@@ -157,7 +158,7 @@ UIColor* BackgroundColor() {
 @end
 
 @interface TabStripController () <DropAndNavigateDelegate,
-                                  TabModelObserver,
+                                  CRWWebStateObserver,
                                   TabStripViewLayoutDelegate,
                                   TabViewDelegate,
                                   WebStateListObserving,
@@ -244,6 +245,14 @@ UIColor* BackgroundColor() {
   std::unique_ptr<WebStateListFaviconDriverObserver>
       _webStateListFaviconObserver;
 
+  // Bridges C++ WebStateObserver methods to this TabStripController.
+  std::unique_ptr<web::WebStateObserverBridge> _webStateObserver;
+
+  // Forwards observer methods for all WebStates in the WebStateList monitored
+  // by the TabStripController.
+  std::unique_ptr<AllWebStateObservationForwarder>
+      _allWebStateObservationForwarder;
+
   API_AVAILABLE(ios(11.0)) DropAndNavigateInteraction* _buttonNewTabInteraction;
 }
 
@@ -266,8 +275,8 @@ UIColor* BackgroundColor() {
 // |isSelected| is passed in here as an optimization, so that the TabView is
 // drawn correctly the first time, without requiring the model to send a
 // -setSelected message to the TabView.
-- (TabView*)tabViewForWebState:(web::WebState*)webState
-                    isSelected:(BOOL)isSelected;
+- (TabView*)createTabViewForWebState:(web::WebState*)webState
+                          isSelected:(BOOL)isSelected;
 
 // Creates and installs the view used to dim unselected tabs.  Does nothing if
 // the view already exists.
@@ -378,8 +387,9 @@ UIColor* BackgroundColor() {
 // Updates the tab switcher button with the current tab count.
 - (void)updateTabCount;
 
-// Updates the tab view fav icon & progress spinner based on the |webState|.
-- (void)updateTabViewForWebState:(web::WebState*)webState;
+// Returns the existing tab view for |webState| or nil if there is no TabView
+// for it.
+- (TabView*)tabViewForWebState:(web::WebState*)webState;
 
 @end
 
@@ -403,12 +413,16 @@ UIColor* BackgroundColor() {
     _closingTabs = [[NSMutableSet alloc] initWithCapacity:5];
 
     _tabModel = tabModel;
-    [_tabModel addObserver:self];
     _webStateListObserver = std::make_unique<WebStateListObserverBridge>(self);
     _tabModel.webStateList->AddObserver(_webStateListObserver.get());
     _webStateListFaviconObserver =
         std::make_unique<WebStateListFaviconDriverObserver>(
             _tabModel.webStateList, self);
+    _webStateObserver = std::make_unique<web::WebStateObserverBridge>(self);
+    // Observe all webStates of this |_tabModel.webStateList|.
+    _allWebStateObservationForwarder =
+        std::make_unique<AllWebStateObservationForwarder>(
+            _tabModel.webStateList, _webStateObserver.get());
     _style = style;
     _dispatcher = dispatcher;
 
@@ -506,7 +520,7 @@ UIColor* BackgroundColor() {
 - (void)dealloc {
   [_tabStripView setDelegate:nil];
   [_tabStripView setLayoutDelegate:nil];
-  [_tabModel removeObserver:self];
+  _allWebStateObservationForwarder.reset();
   _tabModel.webStateList->RemoveObserver(_webStateListObserver.get());
 }
 
@@ -523,7 +537,8 @@ UIColor* BackgroundColor() {
   for (int index = 0; index < webStateList->count(); ++index) {
     web::WebState* webState = webStateList->GetWebStateAt(index);
     BOOL isSelected = index == webStateList->active_index();
-    TabView* view = [self tabViewForWebState:webState isSelected:isSelected];
+    TabView* view = [self createTabViewForWebState:webState
+                                        isSelected:isSelected];
     [_tabArray addObject:view];
     [_tabStripView addSubview:view];
   }
@@ -550,8 +565,8 @@ UIColor* BackgroundColor() {
   return view;
 }
 
-- (TabView*)tabViewForWebState:(web::WebState*)webState
-                    isSelected:(BOOL)isSelected {
+- (TabView*)createTabViewForWebState:(web::WebState*)webState
+                          isSelected:(BOOL)isSelected {
   TabView* view = [[TabView alloc] initWithEmptyView:NO selected:isSelected];
   if (UseRTLLayout())
     [view setTransform:CGAffineTransformMakeScale(-1, 1)];
@@ -964,7 +979,55 @@ UIColor* BackgroundColor() {
 }
 
 #pragma mark -
-#pragma mark WebStateObserving methods
+#pragma mark - CRWWebStateObserver methods
+
+- (void)webStateDidStartLoading:(web::WebState*)webState {
+  // webState can start loading before  didInsertWebState is called, in that
+  // case early return as there is no view to update yet.
+  if (_tabModel.count > _tabArray.count - _closingTabs.count)
+    return;
+
+  if (IsVisibleURLNewTabPage(webState))
+    return;
+
+  TabView* view = [self tabViewForWebState:webState];
+  if (!view) {
+    DCHECK(false) << "Received start loading notification for a Webstate "
+                  << "that is not contained in the WebStateList";
+    return;
+  }
+  [view startProgressSpinner];
+  [view setNeedsDisplay];
+}
+
+- (void)webStateDidStopLoading:(web::WebState*)webState {
+  TabView* view = [self tabViewForWebState:webState];
+  if (!view) {
+    DCHECK(false) << "Received stop loading notification for a Webstate "
+                  << "that is not contained in the WebStateList";
+    return;
+  }
+  // In new Tab case WebState's DidChangeTitle is not called. Make sure to
+  // updated the title here to account for that.
+  [view setTitle:tab_util::GetTabTitle(webState)];
+
+  [view stopProgressSpinner];
+  [view setNeedsDisplay];
+}
+
+- (void)webStateDidChangeTitle:(web::WebState*)webState {
+  TabView* view = [self tabViewForWebState:webState];
+  if (!view) {
+    DCHECK(false) << "Received title change notification for a Webstate "
+                  << "that is not contained in the WebStateList";
+    return;
+  }
+  [view setTitle:tab_util::GetTabTitle(webState)];
+  [view setNeedsDisplay];
+}
+
+#pragma mark -
+#pragma mark WebStateListObserving methods
 
 // Observer method, active WebState changed.
 - (void)webStateList:(WebStateList*)webStateList
@@ -1048,7 +1111,8 @@ UIColor* BackgroundColor() {
     didInsertWebState:(web::WebState*)webState
               atIndex:(int)index
            activating:(BOOL)activating {
-  TabView* view = [self tabViewForWebState:webState isSelected:activating];
+  TabView* view = [self createTabViewForWebState:webState
+                                      isSelected:activating];
   [_tabArray insertObject:view atIndex:[self indexForModelIndex:index]];
   [[self tabStripView] addSubview:view];
 
@@ -1086,38 +1150,15 @@ UIColor* BackgroundColor() {
   }
 }
 
-#pragma mark -
-#pragma mark TabModelObserver methods
-
-// Observer method.
-- (void)tabModel:(TabModel*)model didChangeTab:(Tab*)tab {
-  // didChangeTab is called with each single webState. Some of these changes
-  // may happen before didInsertWebState is called, in that case early return as
-  // there is no view to update yet.
-  if (_tabModel.count > _tabArray.count - _closingTabs.count)
-    return;
-  [self updateTabViewForWebState:tab.webState];
-}
-
 #pragma mark -
 #pragma mark Views and Layout
 
-- (void)updateTabViewForWebState:(web::WebState*)webState {
+- (TabView*)tabViewForWebState:(web::WebState*)webState {
   int modelIndex = _tabModel.webStateList->GetIndexOfWebState(webState);
-  if (modelIndex == WebStateList::kInvalidIndex) {
-    DCHECK(false) << "Received notification for a Webstate that is not "
-                  << "contained in the WebStateList";
-    return;
-  }
+  if (modelIndex == WebStateList::kInvalidIndex)
+    return nil;
   NSUInteger index = [self indexForModelIndex:modelIndex];
-  TabView* view = [_tabArray objectAtIndex:index];
-  [view setTitle:tab_util::GetTabTitle(webState)];
-
-  if (webState->IsLoading() && !IsVisibleURLNewTabPage(webState))
-    [view startProgressSpinner];
-  else
-    [view stopProgressSpinner];
-  [view setNeedsDisplay];
+  return [_tabArray objectAtIndex:index];
 }
 
 - (CGFloat)tabStripVisibleSpace {