Simplify ios session sync logic

SessionSyncService's API is sufficient to achieve the desired
behavior, i.e. distinguish the exact state for tab sync: off,
initial download in progress and done. It also issues a
notification every time that state changes, so there's no need to
monitor updates from ProfileSyncService directly.

Bug: 895455
Change-Id: Icf66328fdde97f833e178f0571dedb248c91beca
Reviewed-on: https://chromium-review.googlesource.com/c/1344029Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612077}

ios/chrome/browser/sync/sync_setup_service.cc

@@ -73,7 +73,7 @@ void SyncSetupService::SetDataTypeEnabled(syncer::ModelType datatype,
     SetSyncEnabled(false);
 }
 
-bool SyncSetupService::UserActionIsRequiredToHaveSyncWork() {
+bool SyncSetupService::UserActionIsRequiredToHaveTabSyncWork() {
   if (!IsSyncEnabled() || !IsDataTypePreferred(syncer::PROXY_TABS)) {
     return true;
   }

ios/chrome/browser/sync/sync_setup_service.h

@@ -44,7 +44,7 @@ class SyncSetupService : public KeyedService {
     kNumberOfSyncableDatatypes
   };
 
-  SyncSetupService(syncer::SyncService* sync_service);
+  explicit SyncSetupService(syncer::SyncService* sync_service);
   ~SyncSetupService() override;
 
   // Returns the |syncer::ModelType| associated to the given
@@ -72,8 +72,8 @@ class SyncSetupService : public KeyedService {
   void SetDataTypeEnabled(syncer::ModelType datatype, bool enabled);
 
   // Returns whether the user needs to enter a passphrase or enable sync to make
-  // sync work.
-  bool UserActionIsRequiredToHaveSyncWork();
+  // tab sync work.
+  bool UserActionIsRequiredToHaveTabSyncWork();
 
   // Returns whether all datatypes are being synced.
   virtual bool IsSyncingAllDataTypes() const;

ios/chrome/browser/ui/recent_tabs/BUILD.gn

@@ -18,7 +18,6 @@ source_set("recent_tabs") {
     ":recent_tabs_ui",
     "resources:show_history",
     "//base",
-    "//components/browser_sync",
     "//components/sessions",
     "//components/sync",
     "//ios/chrome/app/strings",
@@ -58,7 +57,6 @@ source_set("recent_tabs_ui") {
   ]
   deps = [
     "//base",
-    "//components/browser_sync",
     "//components/sessions",
     "//components/strings",
     "//components/sync",
@@ -97,7 +95,7 @@ source_set("unit_tests") {
     ":recent_tabs_ui",
     "//base",
     "//components/browser_sync",
-    "//components/browser_sync:test_support",
+    "//components/sync:test_support_model",
     "//components/sync_sessions",
     "//ios/chrome/browser/browser_state:test_support",
     "//ios/chrome/browser/signin",

ios/chrome/browser/ui/recent_tabs/recent_tabs_mediator.mm

@@ -139,7 +139,7 @@ const CGFloat kFaviconMinWidthHeight = 16;
   DCHECK([self isSignedIn]);
   SyncSetupService* service =
       SyncSetupServiceFactory::GetForBrowserState(_browserState);
-  return !service->UserActionIsRequiredToHaveSyncWork();
+  return !service->UserActionIsRequiredToHaveTabSyncWork();
 }
 
 // Returns whether this profile has any foreign sessions to sync.
@@ -148,25 +148,29 @@ const CGFloat kFaviconMinWidthHeight = 16;
     return SessionsSyncUserState::USER_SIGNED_OUT;
   if (![self isSyncTabsEnabled])
     return SessionsSyncUserState::USER_SIGNED_IN_SYNC_OFF;
-  if ([self hasForeignSessions])
-    return SessionsSyncUserState::USER_SIGNED_IN_SYNC_ON_WITH_SESSIONS;
   if (![self isSyncCompleted])
     return SessionsSyncUserState::USER_SIGNED_IN_SYNC_IN_PROGRESS;
+  if ([self hasForeignSessions])
+    return SessionsSyncUserState::USER_SIGNED_IN_SYNC_ON_WITH_SESSIONS;
   return SessionsSyncUserState::USER_SIGNED_IN_SYNC_ON_NO_SESSIONS;
 }
 
+- (BOOL)isSyncCompleted {
+  sync_sessions::SessionSyncService* service =
+      SessionSyncServiceFactory::GetForBrowserState(_browserState);
+  DCHECK(service);
+  return service->GetOpenTabsUIDelegate() != nullptr;
+}
+
 - (BOOL)hasForeignSessions {
   sync_sessions::SessionSyncService* service =
       SessionSyncServiceFactory::GetForBrowserState(_browserState);
   DCHECK(service);
   sync_sessions::OpenTabsUIDelegate* openTabs =
       service->GetOpenTabsUIDelegate();
+  DCHECK(openTabs);
   std::vector<const sync_sessions::SyncedSession*> sessions;
-  return openTabs ? openTabs->GetAllForeignSessions(&sessions) : NO;
-}
-
-- (BOOL)isSyncCompleted {
-  return _syncedSessionsObserver->IsFirstSyncCycleCompleted();
+  return openTabs->GetAllForeignSessions(&sessions);
 }
 
 #pragma mark - RecentTabsTableViewControllerDelegate

ios/chrome/browser/ui/recent_tabs/synced_sessions_bridge.h

@@ -11,8 +11,6 @@
 
 #include "base/callback_list.h"
 #include "base/macros.h"
-#include "components/sync/driver/sync_service_observer.h"
-#import "ios/chrome/browser/sync/sync_observer_bridge.h"
 #include "services/identity/public/cpp/identity_manager.h"
 
 namespace ios {
@@ -23,7 +21,7 @@ namespace identity {
 class IdentityManager;
 }
 
-@protocol SyncedSessionsObserver<SyncObserverModelBridge>
+@protocol SyncedSessionsObserver
 // Reloads the session data.
 - (void)reloadSessions;
 @end
@@ -33,21 +31,15 @@ namespace synced_sessions {
 // Bridge class that will notify the panel when the remote sessions content
 // change.
 class SyncedSessionsObserverBridge
-    : public SyncObserverBridge,
-      public identity::IdentityManager::Observer {
+    : public identity::IdentityManager::Observer {
  public:
   SyncedSessionsObserverBridge(id<SyncedSessionsObserver> owner,
                                ios::ChromeBrowserState* browserState);
   ~SyncedSessionsObserverBridge() override;
-  // SyncObserverBridge implementation.
-  void OnSyncConfigurationCompleted(syncer::SyncService* sync) override;
   // identity::IdentityManager::Observer implementation.
   void OnPrimaryAccountCleared(
       const AccountInfo& previous_primary_account_info) override;
 
-  // Returns true if the first sync cycle that contains session information is
-  // completed. Returns false otherwise.
-  bool IsFirstSyncCycleCompleted();
   // Returns true if user is signed in.
   bool IsSignedIn();
 
@@ -56,7 +48,6 @@ class SyncedSessionsObserverBridge
 
   __weak id<SyncedSessionsObserver> owner_ = nil;
   identity::IdentityManager* identity_manager_ = nullptr;
-  ios::ChromeBrowserState* browser_state_;
   ScopedObserver<identity::IdentityManager, identity::IdentityManager::Observer>
       identity_manager_observer_;
   std::unique_ptr<base::CallbackList<void()>::Subscription>
@@ -67,4 +58,4 @@ class SyncedSessionsObserverBridge
 
 }  // namespace synced_sessions
 
-#endif  // IOS_CHROME_BROWSER_SYNC_SYNCED_SESSIONS_BRIDGE_H_
+#endif  // IOS_CHROME_BROWSER_UI_RECENT_TABS_SYNCED_SESSIONS_BRIDGE_H_

ios/chrome/browser/ui/recent_tabs/synced_sessions_bridge.mm

@@ -4,14 +4,10 @@
 
 #import "ios/chrome/browser/ui/recent_tabs/synced_sessions_bridge.h"
 
-#include "components/browser_sync/profile_sync_service.h"
 #include "components/sync_sessions/session_sync_service.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/signin/identity_manager_factory.h"
-#include "ios/chrome/browser/sync/profile_sync_service_factory.h"
 #include "ios/chrome/browser/sync/session_sync_service_factory.h"
-#include "ios/chrome/browser/sync/sync_setup_service.h"
-#include "ios/chrome/browser/sync/sync_setup_service_factory.h"
 #include "services/identity/public/cpp/identity_manager.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -25,13 +21,9 @@ namespace synced_sessions {
 SyncedSessionsObserverBridge::SyncedSessionsObserverBridge(
     id<SyncedSessionsObserver> owner,
     ios::ChromeBrowserState* browserState)
-    : SyncObserverBridge(
-          owner,
-          ProfileSyncServiceFactory::GetForBrowserState(browserState)),
-      owner_(owner),
+    : owner_(owner),
       identity_manager_(
           IdentityManagerFactory::GetForBrowserState(browserState)),
-      browser_state_(browserState),
       identity_manager_observer_(this) {
   identity_manager_observer_.Add(identity_manager_);
 
@@ -46,24 +38,6 @@ SyncedSessionsObserverBridge::SyncedSessionsObserverBridge(
 
 SyncedSessionsObserverBridge::~SyncedSessionsObserverBridge() {}
 
-#pragma mark - SyncObserverBridge
-
-void SyncedSessionsObserverBridge::OnSyncConfigurationCompleted(
-    syncer::SyncService* sync) {
-  // TODO(crbug.com/895455): This notification seems redundant because
-  // OnForeignSessionChanged() should be called when the initial sync is
-  // completed.
-  [owner_ reloadSessions];
-}
-
-bool SyncedSessionsObserverBridge::IsFirstSyncCycleCompleted() {
-  // TODO(crbug.com/895455): This could probably be implemented via
-  // SessionSyncService directly and possibly remove all dependencies to
-  // SyncService/SyncSetupService.
-  return SyncSetupServiceFactory::GetForBrowserState(browser_state_)
-      ->IsDataTypeActive(syncer::SESSIONS);
-}
-
 #pragma mark - identity::IdentityManager::Observer
 
 void SyncedSessionsObserverBridge::OnPrimaryAccountCleared(