Closing a guest session clears all browsing history.

chrome/browser/ui/browser.cc

 // Copyright 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 16 matching lines @@
 #include "base/threading/thread_restrictions.h"
 #include "base/time/time.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/app_mode/app_mode_utils.h"
 #include "chrome/browser/autofill/personal_data_manager_factory.h"
 #include "chrome/browser/background/background_contents.h"
 #include "chrome/browser/background/background_contents_service.h"
 #include "chrome/browser/background/background_contents_service_factory.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_shutdown.h"
+#include "chrome/browser/browsing_data/browsing_data_helper.h"
+#include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/character_encoding.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/content_settings/tab_specific_content_settings.h"
 #include "chrome/browser/custom_handlers/protocol_handler_registry.h"
 #include "chrome/browser/custom_handlers/protocol_handler_registry_factory.h"
 #include "chrome/browser/custom_handlers/register_protocol_handler_infobar_delegate.h"
 #include "chrome/browser/custom_handlers/register_protocol_handler_permission_request.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/devtools/devtools_toggle_action.h"
 #include "chrome/browser/devtools/devtools_window.h"
@@ skipping 457 matching lines @@
   // Destroy BrowserExtensionWindowController before the incognito profile
   // is destroyed to make sure the chrome.windows.onRemoved event is sent.
   extension_window_controller_.reset();
 
   // Destroy BrowserInstantController before the incongnito profile is destroyed
   // because the InstantController destructor depends on this profile.
   instant_controller_.reset();
 
   if (profile_->IsOffTheRecord() &&
       !BrowserList::IsOffTheRecordSessionActiveForProfile(profile_)) {
-    // An incognito profile is no longer needed, this indirectly frees
-    // its cache and cookies once it gets destroyed at the appropriate time.
-    ProfileDestroyer::DestroyProfileWhenAppropriate(profile_);
+    if (profile_->IsGuestSession()) {
+      // Clear all browsing data once a Guest Session completes. The Guest
+      // profile has BrowserContextKeyedServices that the Incognito profile
+      // doesn't, so the ProfileDestroyer can't delete it properly.
+      // TODO(mlerman): Delete the guest using an improved ProfileDestroyer.
+      BrowsingDataRemover* data_remover =
+          BrowsingDataRemover::CreateForUnboundedRange(profile_);
+      data_remover->Remove(BrowsingDataRemover::REMOVE_ALL ^
+                               BrowsingDataRemover::REMOVE_DOWNLOADS,

[battre, 2015/02/11 15:19:25]

Looking at
https://developer.chrome.com/extensions/browsingData#method-removeDownloads (I
did not check the code), REMOVE_DOWNLOADS seems to clear the list of downloaded
files but not to delete the files. Maybe REMOVE_ALL is sufficient here.

[Bernhard Bauer, 2015/02/11 16:04:28]

Yup, we never delete downloaded files.

[Mike Lerman, 2015/02/12 15:36:23]

Okay. Done.

+                           BrowsingDataHelper::ALL);
+      // BrowsingDataRemover deletes itself.
+    } else {
+      // An incognito profile is no longer needed, this indirectly frees
+      // its cache and cookies once it gets destroyed at the appropriate time.
+      ProfileDestroyer::DestroyProfileWhenAppropriate(profile_);
+    }
   }
 
   // There may be pending file dialogs, we need to tell them that we've gone
   // away so they don't try and call back to us.
   if (select_file_dialog_.get())
     select_file_dialog_->ListenerDestroyed();
 
   int num_downloads;
   if (OkToCloseWithInProgressDownloads(&num_downloads) ==
           DOWNLOAD_CLOSE_BROWSER_SHUTDOWN &&
@@ skipping 1985 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         ui::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }