chromeos: Break WebUILoginDisplay and SigninScreenHandler coupling on destruction.

So that neither of the two points to an invalid instance.

BUG=chromium-os:29669
TEST=Verify crash in chromium-os:29669 no longer happens.

Review URL: http://codereview.chromium.org/10213003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@133959 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/webui_login_display.cc

@@ -20,6 +20,8 @@ namespace chromeos {
 // WebUILoginDisplay, public: --------------------------------------------------
 
 WebUILoginDisplay::~WebUILoginDisplay() {
+  if (webui_handler_)
+    webui_handler_->ResetSigninScreenHandlerDelegate();
 }
 
 // LoginDisplay implementation: ------------------------------------------------
@@ -59,24 +61,25 @@ void WebUILoginDisplay::OnBeforeUserRemoved(const std::string& username) {
 }
 
 void WebUILoginDisplay::OnUserImageChanged(const User& user) {
-  DCHECK(webui_handler_);
-  webui_handler_->OnUserImageChanged(user);
+  if (webui_handler_)
+    webui_handler_->OnUserImageChanged(user);
 }
 
 void WebUILoginDisplay::OnUserRemoved(const std::string& username) {
-  DCHECK(webui_handler_);
-  webui_handler_->OnUserRemoved(username);
+  if (webui_handler_)
+    webui_handler_->OnUserRemoved(username);
 }
 
 void WebUILoginDisplay::OnFadeOut() {
 }
 
 void WebUILoginDisplay::OnLoginSuccess(const std::string& username) {
-  webui_handler_->OnLoginSuccess(username);
+  if (webui_handler_)
+    webui_handler_->OnLoginSuccess(username);
 }
 
 void WebUILoginDisplay::SetUIEnabled(bool is_enabled) {
-  if (is_enabled)
+  if (webui_handler_ && is_enabled)
     webui_handler_->ClearAndEnablePassword();
 }
 
@@ -89,7 +92,8 @@ void WebUILoginDisplay::ShowError(int error_msg_id,
   VLOG(1) << "Show error, error_id: " << error_msg_id
           << ", attempts:" << login_attempts
           <<  ", help_topic_id: " << help_topic_id;
-  DCHECK(webui_handler_);
+  if (!webui_handler_)
+    return;
 
   std::string error_text;
   switch (error_msg_id) {
@@ -138,7 +142,8 @@ void WebUILoginDisplay::ShowError(int error_msg_id,
 }
 
 void WebUILoginDisplay::ShowGaiaPasswordChanged(const std::string& username) {
-  webui_handler_->ShowGaiaPasswordChanged(username);
+  if (webui_handler_)
+    webui_handler_->ShowGaiaPasswordChanged(username);
 }
 
 // WebUILoginDisplay, SigninScreenHandlerDelegate implementation: --------------
@@ -195,8 +200,8 @@ void WebUILoginDisplay::SetWebUIHandler(
 void WebUILoginDisplay::ShowSigninScreenForCreds(
     const std::string& username,
     const std::string& password) {
-  DCHECK(webui_handler_);
-  webui_handler_->ShowSigninScreenForCreds(username, password);
+  if (webui_handler_)
+    webui_handler_->ShowSigninScreenForCreds(username, password);
 }
 
 const UserList& WebUILoginDisplay::GetUsers() const {

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc

@@ -289,6 +289,8 @@ SigninScreenHandler::~SigninScreenHandler() {
     cookie_remover_->RemoveObserver(this);
   if (key_event_listener_)
     key_event_listener_->RemoveCapsLockObserver(this);
+  if (delegate_)
+    delegate_->SetWebUIHandler(NULL);
   CrosSettings::Get()->RemoveSettingsObserver(kAccountsPrefAllowNewUser, this);
   CrosSettings::Get()->RemoveSettingsObserver(kAccountsPrefAllowGuest, this);
 }
@@ -542,6 +544,10 @@ void SigninScreenHandler::ShowGaiaPasswordChanged(const std::string& username) {
       "login.AccountPickerScreen.updateUserGaiaNeeded", email_value);
 }
 
+void SigninScreenHandler::ResetSigninScreenHandlerDelegate() {
+  SetDelegate(NULL);
+}
+
 void SigninScreenHandler::OnBrowsingDataRemoverDone() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   cookie_remover_ = NULL;

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h

@@ -47,6 +47,7 @@ class LoginDisplayWebUIHandler {
   // Show siginin screen for the given credentials.
   virtual void ShowSigninScreenForCreds(const std::string& username,
                                         const std::string& password) = 0;
+  virtual void ResetSigninScreenHandlerDelegate() = 0;
  protected:
   virtual ~LoginDisplayWebUIHandler() {}
 };
@@ -151,6 +152,7 @@ class SigninScreenHandler : public BaseScreenHandler,
   virtual void ShowSigninScreenForCreds(const std::string& username,
                                         const std::string& password) OVERRIDE;
   virtual void ShowGaiaPasswordChanged(const std::string& username) OVERRIDE;
+  virtual void ResetSigninScreenHandlerDelegate() OVERRIDE;
 
   // BrowsingDataRemover::Observer overrides.
   virtual void OnBrowsingDataRemoverDone() OVERRIDE;