[Extensions] Validate file existence for chrome url overrides

extensions/common/manifest_constants.cc

 // 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.
 
 #include "build/build_config.h"
 #include "extensions/common/manifest_constants.h"
 
 namespace extensions {
 
 namespace manifest_keys {
@@ skipping 275 matching lines @@
     "Cannot claim all URLs in an extent.";
 const char kCannotScriptGallery[] =
     "The extensions gallery cannot be scripted.";
 const char kCannotScriptSigninPage[] =
     "The sign-in page cannot be scripted.";
 const char kChromeVersionTooLow[] =
     "This extension requires * version * or greater.";
 const char kDisabledByPolicy[] =
     "This extension has been disabled by your administrator.";
 const char kExpectString[] = "Expect string value.";
+const char kFileNotFound[] = "File not found: *.";
 const char kInvalidAboutPage[] = "Invalid value for 'about_page'.";
 const char kInvalidAboutPageExpectRelativePath[] =
     "Invalid value for 'about_page'. Value must be a relative path.";
 const char kInvalidAllFrames[] =
     "Invalid value for 'content_scripts[*].all_frames'.";
 const char kInvalidAppIconColor[] = "Invalid value for app.icon_color.";
 const char kInvalidBackground[] =
     "Invalid value for 'background_page'.";
 const char kInvalidBackgroundAllowJsAccess[] =
     "Invalid value for 'background.allow_js_access'.";
@@ skipping 435 matching lines @@
     "'file_system_provider_capabilities' section to be specified in the "
     "manifest.";
 const char kInvalidFileSystemProviderMissingPermission[] =
     "The 'file_system_provider_capabilities' section requires the "
     "'fileSystemProvider' permission to be specified in the manifest.";
 #endif
 
 }  // namespace manifest_errors
 
 }  // namespace extensions