Add new user script injection point: document_idle.

chrome/common/extensions/user_script.h

 // Copyright 2009 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_COMMON_EXTENSIONS_USER_SCRIPT_H_
 #define CHROME_COMMON_EXTENSIONS_USER_SCRIPT_H_
 
 #include <vector>
 #include <string>
 
@@ skipping 10 matching lines @@
 class UserScript {
  public:
   typedef std::vector<URLPattern> PatternList;
 
   // Locations that user scripts can be run inside the document.
   enum RunLocation {
     DOCUMENT_START,  // After the documentElemnet is created, but before
                      // anything else happens.
     DOCUMENT_END,  // After the entire document is parsed. Same as
                    // DOMContentLoaded.
+    DOCUMENT_IDLE,  // Sometime after DOMContentLoaded, as soon as the document
+                    // is "idle". Currently this uses the simple heuristic of:
+                    // min(DOM_CONTENT_LOADED + TIMEOUT, ONLOAD), but no
+                    // particular injection point is guaranteed.
 
     RUN_LOCATION_LAST  // Leave this as the last item.
   };
 
   // Holds actual script file info.
   class File {
    public:
     File(const FilePath& extension_root, const FilePath& relative_path,
          const GURL& url):
         extension_root_(extension_root),
@@ skipping 40 matching lines @@
     // The script content. It can be set to either loaded_content_ or
     // externally allocated string.
     base::StringPiece external_content_;
 
     // Set when the content is loaded by LoadContent
     std::string content_;
   };
 
   typedef std::vector<File> FileList;
 
-  // Constructor. Default the run location to document end, which is like
-  // Greasemonkey and probably more useful for typical scripts.
-  UserScript() : run_location_(DOCUMENT_END) {}
+  // Constructor. Default the run location to document idle, which is similar
+  // to Greasemonkey but should result in better page load times for fast-
+  // loading pages.
+  UserScript() : run_location_(DOCUMENT_IDLE) {}
 
   // The place in the document to run the script.
   RunLocation run_location() const { return run_location_; }
   void set_run_location(RunLocation location) { run_location_ = location; }
 
   // The globs, if any, that determine which pages this script runs against.
   // These are only used with "standalone" Greasemonkey-like user scripts.
   const std::vector<std::string>& globs() const { return globs_; }
   void add_glob(const std::string& glob) { globs_.push_back(glob); }
   void clear_globs() { globs_.clear(); }
@@ skipping 51 matching lines @@
   FileList css_scripts_;
 
   // The ID of the extension this script is a part of, if any. Can be empty if
   // the script is a "standlone" user script.
   std::string extension_id_;
 };
 
 typedef std::vector<UserScript> UserScriptList;
 
 #endif  // CHROME_COMMON_EXTENSIONS_USER_SCRIPT_H_