Add PerAppSettingsService and use it to remember what desktop apps should create windows on.

chrome/browser/apps/per_app_settings_service.h

Index: chrome/browser/apps/per_app_settings_service.h
diff --git a/chrome/browser/apps/per_app_settings_service.h b/chrome/browser/apps/per_app_settings_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..463aec12bca3c01b79af69bb55f83477295e6f8e
--- /dev/null
+++ b/chrome/browser/apps/per_app_settings_service.h
@@ -0,0 +1,36 @@
+// Copyright 2013 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.
+
+#ifndef CHROME_BROWSER_APPS_PER_APP_SETTINGS_SERVICE_H_
+#define CHROME_BROWSER_APPS_PER_APP_SETTINGS_SERVICE_H_
+
+#include <map>
+#include <string>
+
+#include "chrome/browser/ui/host_desktop.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+
+// Stores settings for apps that only persist until the browser context is
+// destroyed.
+class PerAppSettingsService : public BrowserContextKeyedService {
+ public:
+  PerAppSettingsService();
+  virtual ~PerAppSettingsService();
+
+  // Sets/gets the desktop that |app_id| was last launched from.
+  void SetDesktopLastLaunchedFrom(
+      const std::string& app_id, chrome::HostDesktopType host);
+  chrome::HostDesktopType GetDesktopLastLaunchedFrom(
+      const std::string& app_id) const;
+  bool HasDesktopLastLaunchedFrom(const std::string& app_id) const;
+
+ private:
+  typedef std::map<std::string, chrome::HostDesktopType> DesktopMap;
+  DesktopMap default_desktops_;
+
+  DISALLOW_COPY_AND_ASSIGN(PerAppSettingsService);
+};
+
+#endif  // CHROME_BROWSER_APPS_PER_APP_SETTINGS_SERVICE_H_
+