Change the platform app manifest structure.

chrome/common/extensions/extension_manifest_constants.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/common/extensions/extension_manifest_constants.h"
 
 namespace extension_manifest_keys {
 
 const char kAllFrames[] = "all_frames";
 const char kAltKey[] = "altKey";
@@ skipping 67 matching lines @@
 const char kPageAction[] = "page_action";
 const char kPageActionDefaultIcon[] = "default_icon";
 const char kPageActionDefaultPopup[] = "default_popup";
 const char kPageActionDefaultTitle[] = "default_title";
 const char kPageActionIcons[] = "icons";
 const char kPageActionId[] = "id";
 const char kPageActionPopup[] = "popup";
 const char kPageActionPopupPath[] = "path";
 const char kPageActions[] = "page_actions";
 const char kPermissions[] = "permissions";
-const char kPlatformApp[] = "platform_app";
+const char kPlatformAppBackground[] = "app.background";
+const char kPlatformAppBackgroundPage[] = "app.background.page";
+const char kPlatformAppBackgroundScripts[] = "app.background.scripts";
 const char kPlugins[] = "plugins";
 const char kPluginsPath[] = "path";
 const char kPluginsPublic[] = "public";
 const char kPublicKey[] = "key";
 const char kRequirements[] = "requirements";
 const char kRunAt[] = "run_at";
 const char kSandboxedPages[] = "sandboxed_pages.pages";
 const char kSandboxedPagesCSP[] = "sandboxed_pages.content_security_policy";
 const char kShiftKey[] = "shiftKey";
 const char kShortcutKey[] = "shortcutKey";
@@ skipping 366 matching lines @@
     "At least one js or css file is required for 'content_scripts[*]'.";
 const char kMultipleOverrides[] =
     "An extension cannot override more than one page.";
 const char kNoWildCardsInPaths[] =
   "Wildcards are not allowed in extent URL pattern paths.";
 const char kOneUISurfaceOnly[] =
     "Only one of 'browser_action', 'page_action', and 'app' can be specified.";
 const char kPermissionNotAllowed[] =
     "Access to permission '*' denied.";
 const char kPlatformAppFlagRequired[] =
     "Loading platform_app extension type is turned off by default. "

[miket_OOO, 2012/06/07 21:34:19]

If we want to be platform_app-clean after this CL, then this error should be
changed, too.

[Mihai Parparita -not on Chrome, 2012/06/07 21:40:01]

I think there's more strings than just these, so I'll do it in a follow-up CL. I
filed http://crbug.com/131688.

     "You can enable this type with the --enable-platform-apps "
     "command-line flag.";
+const char kPlatformAppInvalidBackgroundPage[] =
+    "Platform app background pages are specified via the "
+    "app.background.page key.";

[miket_OOO, 2012/06/07 21:34:19]

Do we want to call these just "apps" rather than "platform apps"? Or is that too
generic?

[Mihai Parparita -not on Chrome, 2012/06/07 21:40:01]

Same as above (and see discussion in my bug comment about naming).

+const char kPlatformAppInvalidBackgroundScripts[] =
+    "Platform app background scripts are specified via the "
+    "app.background.scripts key.";
 const char kPlatformAppNeedsManifestVersion2[] =
     "Platform apps need manifest_version set to >= 2";
 const char kReservedMessageFound[] =
     "Reserved key * found in message catalog.";
 const char kWebRequestConflictsWithLazyBackground[] =
     "The 'webRequest' API cannot be used with event pages.";
 #if defined(OS_CHROMEOS)
 const char kIllegalPlugins[] =
     "Extensions cannot install plugins on Chrome OS";
 #endif
 }  // namespace extension_manifest_errors