Add support for temporarily disabling sync.

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index 99299b8d7efb72c9139a19144b0b7cb352e55871..b74136eb2a6257bc5e3d473b992b18151609410e 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -188,19 +188,20 @@ void ProfileSyncService::Initialize() {
     signin_->Initialize(profile_);
   }
 
-  if (!HasSyncSetupCompleted()) {
-    // If autostart is enabled, but we haven't completed sync setup, try to
-    // start sync anyway (it's possible we crashed/shutdown after logging in
-    // but before the backend finished initializing the last time).
-    if (auto_start_enabled_ && !sync_prefs_.IsStartSuppressed() &&
-        AreCredentialsAvailable()) {
+  StartUpIfNotSuppressed();
+}
+
+void ProfileSyncService::StartUpIfNotSuppressed() {
+  if (!sync_prefs_.IsStartSuppressed() && AreCredentialsAvailable()) {
+    if (HasSyncSetupCompleted() || auto_start_enabled_) {
+      // If sync setup has completed we always start the backend.
+      // If autostart is enabled, but we haven't completed sync setup, we try to
+      // start sync anyway, since it's possible we crashed/shutdown after
+      // logging in but before the backend finished initializing the last time.
+      // Note that if we haven't finished setting up sync, backend bring up will
+      // be done by the wizard.
       StartUp();
     }
-  } else if (AreCredentialsAvailable()) {
-    // If we have credentials and sync setup finished, autostart the backend.
-    // Note that if we haven't finished setting up sync, backend bring up will
-    // be done by the wizard.
-    StartUp();
   }
 }
 
@@ -1512,6 +1513,22 @@ bool ProfileSyncService::ShouldPushChanges() {
   return data_type_manager_->state() == DataTypeManager::CONFIGURED;
 }
 
+void ProfileSyncService::StopSyncAndSuppressStartUp() {
+  sync_prefs_.SetStartSuppressed(true);
+  Shutdown(false);
+}
+
+void ProfileSyncService::DisableSyncSuppressionAndStartUpSync() {
+  DCHECK(profile_);
+  sync_prefs_.SetStartSuppressed(false);
+  // Set username in SigninManager, as SigninManager::OnGetUserInfoSuccess
+  // is never called for some clients.
+  if (signin_->GetUsername().empty()) {
+    signin_->SetUsername(profile_->GetProfileName());

[akalin, 2011/10/26 18:53:09]

What is the username used for?  Isn't the profile name just some arbitrary name
(like "Profile0") and not related to the sync account?  If it's something
platform-specific maybe that should be mentioned, and/or this should be put in
an ifdef.

+  }
+  StartUpIfNotSuppressed();
+}
+
 void ProfileSyncService::AcknowledgeSyncedTypes() {
   syncable::ModelTypeSet registered_types;
   GetRegisteredDataTypes(&registered_types);