Introduce HostID and de-couple Extensions from "script injection System" [browser side]

extensions/common/user_script.h

Index: extensions/common/user_script.h
diff --git a/extensions/common/user_script.h b/extensions/common/user_script.h
index 5a2731536b2237699a1c76f54aa778d2af9643e8..6069161e8fb4dc0bd8e58c67163a473340bad339 100644
--- a/extensions/common/user_script.h
+++ b/extensions/common/user_script.h
@@ -11,6 +11,7 @@
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/strings/string_piece.h"
+#include "extensions/common/host_id.h"
 #include "extensions/common/url_pattern.h"
 #include "extensions/common/url_pattern_set.h"
 #include "url/gurl.h"
@@ -194,8 +195,10 @@ class UserScript {
   FileList& css_scripts() { return css_scripts_; }
   const FileList& css_scripts() const { return css_scripts_; }
 
-  const std::string& extension_id() const { return extension_id_; }
-  void set_extension_id(const std::string& id) { extension_id_ = id; }
+  const std::string& extension_id() const { return host_id_.id(); }
+
+  const HostID& host_id() const { return host_id_; }
+  void set_host_id(const HostID& host_id) { host_id_ = host_id; }
 
   int id() const { return user_script_id_; }
   void set_id(int id) { user_script_id_ = id; }
@@ -203,7 +206,7 @@ class UserScript {
   bool is_incognito_enabled() const { return incognito_enabled_; }
   void set_incognito_enabled(bool enabled) { incognito_enabled_ = enabled; }
 
-  bool is_standalone() const { return extension_id_.empty(); }
+  bool is_standalone() const { return extension_id().empty(); }
 
   // Returns true if the script should be applied to the specified URL, false
   // otherwise.
@@ -222,6 +225,7 @@ class UserScript {
   // Pickle helper functions used to pickle the individual types of components.
   void PickleGlobs(::Pickle* pickle,
                    const std::vector<std::string>& globs) const;
+  void PickleHostID(::Pickle* pickle, const HostID& host_id) const;
   void PickleURLPatternSet(::Pickle* pickle,
                            const URLPatternSet& pattern_list) const;
   void PickleScripts(::Pickle* pickle, const FileList& scripts) const;
@@ -229,6 +233,9 @@ class UserScript {
   // Unpickle helper functions used to unpickle individual types of components.
   void UnpickleGlobs(const ::Pickle& pickle, PickleIterator* iter,
                      std::vector<std::string>* globs);
+  void UnpickleHostID(const ::Pickle& pickle,
+                      PickleIterator* iter,
+                      HostID* host_id);
   void UnpickleURLPatternSet(const ::Pickle& pickle, PickleIterator* iter,
                              URLPatternSet* pattern_list);
   void UnpickleScripts(const ::Pickle& pickle, PickleIterator* iter,
@@ -267,9 +274,9 @@ class UserScript {
   // List of css scripts defined in content_scripts
   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_;
+  // The ID of the host this script is a part of. The |ID| of the
+  // |host_id| can be empty if the script is a "standlone" user script.
+  HostID host_id_;
 
   // The globally-unique id associated with this user script. Defaults to
   // -1 for invalid.