Remove TabModelList from SessionEventRouter

Removes TabModelList from IOSChromeLocalSessionEventRouter. Instead
the observer uses an AllWebStateListObservationRegistrar and an inner
observer class to perform the same updates.

Bug: 1050147

Change-Id: Ic9d00b601135764b44e91c1b999fa5d2c8662755
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2249670
Commit-Queue: Mark Cogan <marq@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780272}

ios/chrome/browser/sync/sessions/BUILD.gn

@@ -17,6 +17,7 @@ source_set("sessions") {
     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/history",
+    "//ios/chrome/browser/main:public",
     "//ios/chrome/browser/sync/glue",
     "//ios/chrome/browser/tabs",
     "//ios/chrome/browser/web_state_list",

ios/chrome/browser/sync/sessions/ios_chrome_local_session_event_router.h

@@ -14,11 +14,11 @@
 #include "base/macros.h"
 #include "components/sync/model/syncable_service.h"
 #include "components/sync_sessions/local_session_event_router.h"
-#import "ios/chrome/browser/tabs/tab_model_list_observer.h"
 #include "ios/chrome/browser/web_state_list/web_state_list_observer.h"
 #include "ios/web/public/web_state_observer.h"
 
 class ChromeBrowserState;
+class AllWebStateListObservationRegistrar;
 
 namespace sync_sessions {
 class SyncSessionsClient;
@@ -27,10 +27,7 @@ class SyncSessionsClient;
 // A LocalEventRouter that drives session sync via observation of
 // web::WebState-related events.
 class IOSChromeLocalSessionEventRouter
-    : public sync_sessions::LocalSessionEventRouter,
-      public web::WebStateObserver,
-      public WebStateListObserver,
-      public TabModelListObserver {
+    : public sync_sessions::LocalSessionEventRouter {
  public:
   IOSChromeLocalSessionEventRouter(
       ChromeBrowserState* browser_state,
@@ -43,43 +40,54 @@ class IOSChromeLocalSessionEventRouter
       sync_sessions::LocalSessionEventHandler* handler) override;
   void Stop() override;
 
-  // TabModelListObserver:
-  void TabModelRegisteredWithBrowserState(
-      TabModel* tab_model,
-      ChromeBrowserState* browser_state) override;
-  void TabModelUnregisteredFromBrowserState(
-      TabModel* tab_model,
-      ChromeBrowserState* browser_state) override;
-
-  // web::WebStateObserver:
-  void TitleWasSet(web::WebState* web_state) override;
-  void DidFinishNavigation(web::WebState* web_state,
-                           web::NavigationContext* navigation_context) override;
-  void PageLoaded(
-      web::WebState* web_state,
-      web::PageLoadCompletionStatus load_completion_status) override;
-  void DidChangeBackForwardState(web::WebState* web_state) override;
-  void WebStateDestroyed(web::WebState* web_state) override;
+ private:
+  // Observer implementation for each browser state.
+  class Observer : public WebStateListObserver, public web::WebStateObserver {
+   public:
+    explicit Observer(IOSChromeLocalSessionEventRouter* session_router);
+    Observer(const Observer&) = delete;
+    Observer& operator=(const Observer&) = delete;
+    ~Observer() override;
 
-  // web::WebStateListObserver:
+   private:
+    // WebStateListObserver:
     void WebStateInsertedAt(WebStateList* web_state_list,
                             web::WebState* web_state,
                             int index,
                             bool activating) override;
+    void WebStateDetachedAt(WebStateList* web_state_list,
+                            web::WebState* web_state,
+                            int index) override;
     void WebStateReplacedAt(WebStateList* web_state_list,
                             web::WebState* old_web_state,
                             web::WebState* new_web_state,
                             int index) override;
-  void WebStateDetachedAt(WebStateList* web_state_list,
-                          web::WebState* web_state,
-                          int index) override;
     void WillBeginBatchOperation(WebStateList* web_state_list) override;
     void BatchOperationEnded(WebStateList* web_state_list) override;
 
- private:
-  // Methods to add and remove WebStateList observer.
-  void StartObservingWebStateList(WebStateList* web_state_list);
-  void StopObservingWebStateList(WebStateList* web_state_list);
+    // web::WebStateObserver:
+    void TitleWasSet(web::WebState* web_state) override;
+    void DidFinishNavigation(
+        web::WebState* web_state,
+        web::NavigationContext* navigation_context) override;
+    void PageLoaded(
+        web::WebState* web_state,
+        web::PageLoadCompletionStatus load_completion_status) override;
+    void DidChangeBackForwardState(web::WebState* web_state) override;
+    void WebStateDestroyed(web::WebState* web_state) override;
+
+    IOSChromeLocalSessionEventRouter* router_;
+  };
+
+  // Observation registrars for each browser state; each one owns an instance
+  // of IOSChromeLocalSessionEventRouter::Observer.
+  std::set<std::unique_ptr<AllWebStateListObservationRegistrar>> registrars_;
+
+  // Called before the Batch operation starts for a web state list.
+  void OnSessionEventStarting();
+
+  // Called when Batch operation is completed for a web state list.
+  void OnSessionEventEnded();
 
   // Called when a tab is parented.
   void OnTabParented(web::WebState* web_state);
@@ -88,7 +96,6 @@ class IOSChromeLocalSessionEventRouter
   void OnWebStateChange(web::WebState* web_state);
 
   sync_sessions::LocalSessionEventHandler* handler_;
-  ChromeBrowserState* const browser_state_;
   sync_sessions::SyncSessionsClient* const sessions_client_;
   syncer::SyncableService::StartSyncFlare flare_;
 

ios/chrome/browser/sync/sessions/ios_chrome_local_session_event_router.mm

@@ -14,10 +14,9 @@
 #include "components/sync_sessions/synced_tab_delegate.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/history/history_service_factory.h"
+#import "ios/chrome/browser/main/all_web_state_list_observation_registrar.h"
 #include "ios/chrome/browser/sync/glue/sync_start_util.h"
 #include "ios/chrome/browser/sync/ios_chrome_synced_tab_delegate.h"
-#import "ios/chrome/browser/tabs/tab_model.h"
-#import "ios/chrome/browser/tabs/tab_model_list.h"
 #include "ios/chrome/browser/tabs/tab_parenting_global_observer.h"
 #import "ios/chrome/browser/web_state_list/web_state_list.h"
 
@@ -41,7 +40,6 @@ IOSChromeLocalSessionEventRouter::IOSChromeLocalSessionEventRouter(
     sync_sessions::SyncSessionsClient* sessions_client,
     const syncer::SyncableService::StartSyncFlare& flare)
     : handler_(NULL),
-      browser_state_(browser_state),
       sessions_client_(sessions_client),
       flare_(flare) {
   tab_parented_subscription_ =
@@ -49,35 +47,20 @@ IOSChromeLocalSessionEventRouter::IOSChromeLocalSessionEventRouter(
           base::Bind(&IOSChromeLocalSessionEventRouter::OnTabParented,
                      base::Unretained(this)));
 
-  for (TabModel* tab_model in TabModelList::GetTabModelsForChromeBrowserState(
-           browser_state_)) {
-    StartObservingWebStateList(tab_model.webStateList);
-  }
-
-  TabModelList::AddObserver(this);
+  registrars_.insert(std::make_unique<AllWebStateListObservationRegistrar>(
+      browser_state, std::make_unique<Observer>(this),
+      AllWebStateListObservationRegistrar::Mode::REGULAR));
 }
 
-IOSChromeLocalSessionEventRouter::~IOSChromeLocalSessionEventRouter() {
-  for (TabModel* tab_model in TabModelList::GetTabModelsForChromeBrowserState(
-           browser_state_)) {
-    StopObservingWebStateList(tab_model.webStateList);
-  }
-  TabModelList::RemoveObserver(this);
-}
+IOSChromeLocalSessionEventRouter::~IOSChromeLocalSessionEventRouter() {}
 
-void IOSChromeLocalSessionEventRouter::TabModelRegisteredWithBrowserState(
-    TabModel* tab_model,
-    ChromeBrowserState* browser_state) {
-  StartObservingWebStateList(tab_model.webStateList);
-}
+IOSChromeLocalSessionEventRouter::Observer::Observer(
+    IOSChromeLocalSessionEventRouter* session_router)
+    : router_(session_router) {}
 
-void IOSChromeLocalSessionEventRouter::TabModelUnregisteredFromBrowserState(
-    TabModel* tab_model,
-    ChromeBrowserState* browser_state) {
-  StopObservingWebStateList(tab_model.webStateList);
-}
+IOSChromeLocalSessionEventRouter::Observer::~Observer() {}
 
-void IOSChromeLocalSessionEventRouter::WebStateInsertedAt(
+void IOSChromeLocalSessionEventRouter::Observer::WebStateInsertedAt(
     WebStateList* web_state_list,
     web::WebState* web_state,
     int index,
@@ -85,81 +68,72 @@ void IOSChromeLocalSessionEventRouter::WebStateInsertedAt(
   web_state->AddObserver(this);
 }
 
-void IOSChromeLocalSessionEventRouter::WebStateReplacedAt(
+void IOSChromeLocalSessionEventRouter::Observer::WebStateReplacedAt(
     WebStateList* web_state_list,
     web::WebState* old_web_state,
     web::WebState* new_web_state,
     int index) {
-  OnWebStateChange(old_web_state);
+  router_->OnWebStateChange(old_web_state);
   old_web_state->RemoveObserver(this);
   DCHECK(new_web_state);
   new_web_state->AddObserver(this);
 }
 
-void IOSChromeLocalSessionEventRouter::WebStateDetachedAt(
+void IOSChromeLocalSessionEventRouter::Observer::WebStateDetachedAt(
     WebStateList* web_state_list,
     web::WebState* web_state,
     int index) {
-  OnWebStateChange(web_state);
+  router_->OnWebStateChange(web_state);
   web_state->RemoveObserver(this);
 }
 
-void IOSChromeLocalSessionEventRouter::TitleWasSet(web::WebState* web_state) {
-  OnWebStateChange(web_state);
+void IOSChromeLocalSessionEventRouter::Observer::TitleWasSet(
+    web::WebState* web_state) {
+  router_->OnWebStateChange(web_state);
 }
 
-void IOSChromeLocalSessionEventRouter::DidFinishNavigation(
+void IOSChromeLocalSessionEventRouter::Observer::DidFinishNavigation(
     web::WebState* web_state,
     web::NavigationContext* navigation_context) {
-  OnWebStateChange(web_state);
+  router_->OnWebStateChange(web_state);
 }
 
-void IOSChromeLocalSessionEventRouter::PageLoaded(
+void IOSChromeLocalSessionEventRouter::Observer::PageLoaded(
     web::WebState* web_state,
     web::PageLoadCompletionStatus load_completion_status) {
-  OnWebStateChange(web_state);
+  router_->OnWebStateChange(web_state);
 }
 
-void IOSChromeLocalSessionEventRouter::DidChangeBackForwardState(
+void IOSChromeLocalSessionEventRouter::Observer::DidChangeBackForwardState(
     web::WebState* web_state) {
-  OnWebStateChange(web_state);
+  router_->OnWebStateChange(web_state);
 }
 
-void IOSChromeLocalSessionEventRouter::WebStateDestroyed(
+void IOSChromeLocalSessionEventRouter::Observer::WebStateDestroyed(
     web::WebState* web_state) {
-  OnWebStateChange(web_state);
+  router_->OnWebStateChange(web_state);
   web_state->RemoveObserver(this);
 }
 
-void IOSChromeLocalSessionEventRouter::StartObservingWebStateList(
-    WebStateList* web_state_list) {
-  web_state_list->AddObserver(this);
-  for (int index = 0; index < web_state_list->count(); ++index) {
-    web::WebState* web_state = web_state_list->GetWebStateAt(index);
-    web_state->AddObserver(this);
-  }
+void IOSChromeLocalSessionEventRouter::OnTabParented(web::WebState* web_state) {
+  OnWebStateChange(web_state);
 }
 
-void IOSChromeLocalSessionEventRouter::StopObservingWebStateList(
+void IOSChromeLocalSessionEventRouter::Observer::WillBeginBatchOperation(
     WebStateList* web_state_list) {
-  for (int index = 0; index < web_state_list->count(); ++index) {
-    web::WebState* web_state = web_state_list->GetWebStateAt(index);
-    web_state->RemoveObserver(this);
-  }
-  web_state_list->RemoveObserver(this);
+  router_->OnSessionEventStarting();
 }
 
-void IOSChromeLocalSessionEventRouter::OnTabParented(web::WebState* web_state) {
-  OnWebStateChange(web_state);
+void IOSChromeLocalSessionEventRouter::Observer::BatchOperationEnded(
+    WebStateList* web_state_list) {
+  router_->OnSessionEventEnded();
 }
 
-void IOSChromeLocalSessionEventRouter::WillBeginBatchOperation(
-    WebStateList* web_state_list) {
+void IOSChromeLocalSessionEventRouter::OnSessionEventStarting() {
   batch_in_progress_++;
 }
 
-void IOSChromeLocalSessionEventRouter::BatchOperationEnded(
-    WebStateList* web_state_list) {
+void IOSChromeLocalSessionEventRouter::OnSessionEventEnded() {
   DCHECK(batch_in_progress_ > 0);
   batch_in_progress_--;
   if (batch_in_progress_)