Fixed null pointer crash in ExtensionSettingsHandler.

chrome/browser/ui/webui/extensions/extension_settings_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/extensions/extension_settings_handler.h"
 
 #include "apps/app_load_service.h"
 #include "apps/app_restore_service.h"
 #include "apps/app_window.h"
 #include "apps/app_window_registry.h"
@@ skipping 825 matching lines @@
 
 void ExtensionSettingsHandler::HandleEnableMessage(
     const base::ListValue* args) {
   CHECK_EQ(2U, args->GetSize());
   std::string extension_id, enable_str;
   CHECK(args->GetString(0, &extension_id));
   CHECK(args->GetString(1, &enable_str));
 
   const Extension* extension =
       extension_service_->GetInstalledExtension(extension_id);
-  if (!extension ||
-      !management_policy_->UserMayModifySettings(extension, NULL)) {
-    LOG(ERROR) << "Attempt to enable an extension that is non-usermanagable was"
-               << "made. Extension id: " << extension->id();
+  if (!extension)
+    return;
+
+  if (!management_policy_->UserMayModifySettings(extension, NULL)) {
+    LOG(ERROR) << "An attempt was made to enable an extension that is "
+               << "non-usermanagable. Extension id: " << extension->id();
     return;
   }
 
   if (enable_str == "true") {
     ExtensionPrefs* prefs = ExtensionPrefs::Get(extension_service_->profile());
     if (prefs->DidExtensionEscalatePermissions(extension_id)) {
       ShowExtensionDisabledDialog(
           extension_service_, web_ui()->GetWebContents(), extension);
     } else if ((prefs->GetDisableReasons(extension_id) &
                    Extension::DISABLE_UNSUPPORTED_REQUIREMENT) &&
@@ skipping 50 matching lines @@
   CHECK_EQ(2U, args->GetSize());
   std::string extension_id, allow_str;
   CHECK(args->GetString(0, &extension_id));
   CHECK(args->GetString(1, &allow_str));
   const Extension* extension =
       extension_service_->GetInstalledExtension(extension_id);
   if (!extension)
     return;
 
   if (!management_policy_->UserMayModifySettings(extension, NULL)) {
-    LOG(ERROR) << "Attempt to change allow file access of an extension that is "
-               << "non-usermanagable was made. Extension id : "
+    LOG(ERROR) << "An attempt was made to change allow file access of an"
+               << " extension that is non-usermanagable. Extension id : "
                << extension->id();
     return;
   }
 
   util::SetAllowFileAccess(
       extension_id, extension_service_->profile(), allow_str == "true");
 }
 
 void ExtensionSettingsHandler::HandleUninstallMessage(
     const base::ListValue* args) {
   CHECK_EQ(1U, args->GetSize());
   std::string extension_id;
   CHECK(args->GetString(0, &extension_id));
   const Extension* extension =
       extension_service_->GetInstalledExtension(extension_id);
   if (!extension)
     return;
 
   if (!management_policy_->UserMayModifySettings(extension, NULL)) {
-    LOG(ERROR) << "Attempt to uninstall an extension that is non-usermanagable "
-               << "was made. Extension id : " << extension->id();
+    LOG(ERROR) << "An attempt was made to uninstall an extension that is "
+               << "non-usermanagable. Extension id : " << extension->id();
     return;
   }
 
   if (!extension_id_prompting_.empty())
     return;  // Only one prompt at a time.
 
   extension_id_prompting_ = extension_id;
 
   GetExtensionUninstallDialog()->ConfirmUninstall(extension);
 }
@@ skipping 294 matching lines @@
     extension_service_->EnableExtension(extension_id);
   } else {
     ExtensionErrorReporter::GetInstance()->ReportError(
         base::UTF8ToUTF16(JoinString(requirement_errors, ' ')),
         true /* be noisy */);
   }
   requirements_checker_.reset();
 }
 
 }  // namespace extensions