cros: Fix crash in lock screen when fingerprint unlock is available.

Make session observer to be ScopedObserver so it remove itself when out
of scope.
Also add AllowJavascript in some JS call hander.

Bug: 876467
Change-Id: If7cd1c2fe42024708027bee5f87855244c7a4ea9
Reviewed-on: https://chromium-review.googlesource.com/1183590Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585094}

chrome/browser/ui/webui/settings/chromeos/fingerprint_handler.cc

@@ -55,7 +55,10 @@ std::unique_ptr<base::DictionaryValue> GetFingerprintsInfo(
 }  // namespace
 
 FingerprintHandler::FingerprintHandler(Profile* profile)
-    : profile_(profile), binding_(this), weak_ptr_factory_(this) {
+    : profile_(profile),
+      binding_(this),
+      session_observer_(this),
+      weak_ptr_factory_(this) {
   service_manager::Connector* connector =
       content::ServiceManagerConnection::GetForProcess()->GetConnector();
   connector->BindInterface(device::mojom::kServiceName, &fp_service_);
@@ -110,12 +113,11 @@ void FingerprintHandler::RegisterMessages() {
 void FingerprintHandler::OnJavascriptAllowed() {
   // SessionManager may not exist in some tests.
   if (SessionManager::Get())
-    SessionManager::Get()->AddObserver(this);
+    session_observer_.Add(SessionManager::Get());
 }
 
 void FingerprintHandler::OnJavascriptDisallowed() {
-  if (SessionManager::Get())
-    SessionManager::Get()->RemoveObserver(this);
+  session_observer_.RemoveAll();
 }
 
 void FingerprintHandler::OnRestarted() {}
@@ -214,6 +216,8 @@ void FingerprintHandler::HandleGetNumFingerprints(const base::ListValue* args) {
 }
 
 void FingerprintHandler::HandleStartEnroll(const base::ListValue* args) {
+  AllowJavascript();
+
   // Determines what the newly added fingerprint's name should be.
   for (int i = 1; i <= kMaxAllowedFingerprints; ++i) {
     std::string fingerprint_name = l10n_util::GetStringFUTF8(
@@ -228,6 +232,7 @@ void FingerprintHandler::HandleStartEnroll(const base::ListValue* args) {
 
 void FingerprintHandler::HandleCancelCurrentEnroll(
     const base::ListValue* args) {
+  AllowJavascript();
   fp_service_->CancelCurrentEnrollSession(
       base::Bind(&FingerprintHandler::OnCancelCurrentEnrollSession,
                  weak_ptr_factory_.GetWeakPtr()));
@@ -307,11 +312,13 @@ void FingerprintHandler::OnSetRecordLabel(const std::string& callback_id,
 
 void FingerprintHandler::HandleStartAuthentication(
     const base::ListValue* args) {
+  AllowJavascript();
   fp_service_->StartAuthSession();
 }
 
 void FingerprintHandler::HandleEndCurrentAuthentication(
     const base::ListValue* args) {
+  AllowJavascript();
   fp_service_->EndCurrentAuthSession(
       base::Bind(&FingerprintHandler::OnEndCurrentAuthSession,
                  weak_ptr_factory_.GetWeakPtr()));

chrome/browser/ui/webui/settings/chromeos/fingerprint_handler.h

@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_FINGERPRINT_HANDLER_H_
 
 #include "base/containers/flat_map.h"
+#include "base/scoped_observer.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
 #include "components/session_manager/core/session_manager_observer.h"
 #include "mojo/public/cpp/bindings/binding.h"
@@ -17,6 +18,10 @@ namespace base {
 class ListValue;
 }  // namespace base
 
+namespace session_manager {
+class SessionManager;
+}  // namespace session_manager
+
 namespace chromeos {
 namespace settings {
 
@@ -76,6 +81,9 @@ class FingerprintHandler : public ::settings::SettingsPageUIHandler,
 
   device::mojom::FingerprintPtr fp_service_;
   mojo::Binding<device::mojom::FingerprintObserver> binding_;
+  ScopedObserver<session_manager::SessionManager,
+                 session_manager::SessionManagerObserver>
+      session_observer_;
 
   base::WeakPtrFactory<FingerprintHandler> weak_ptr_factory_;