Refactoring: de-couple Extensions from "script injection System" [render side] : 1

extensions/common/host_id.h

 // Copyright 2015 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 EXTENSIONS_COMMON_HOST_ID_H_
 #define EXTENSIONS_COMMON_HOST_ID_H_
 
 #include <string>
 
 // IDs of hosts who own user scripts.
 // A HostID is immutable after creation.
 struct HostID {
   enum HostType { EXTENSIONS, WEBUI };
 
+  // The default id of the instance that host will inject the script.
+  // If the instance is a regular tab, the |instance_id| is 0; if the instance
+  // is <webview>, the |instance_id| is a unique number that is bigger than 0.
+  static const int kDefaultInstanceId;
+
   HostID() {}
   HostID(HostType type, const std::string& id)
       : type_(type), id_(id) {}

[Devlin, 2015/02/11 00:00:48]

Since we need a .cc for the definition of kDefaultInstanceId, may as well move
these there, too.

[Xi Han, 2015/02/11 16:00:23]

Moved.

+  HostID(const HostID& host_id)
+      : type_(host_id.type()),
+        id_(host_id.id()) {}
 
   bool operator<(const HostID& host_id) const {
     if (type_ != host_id.type())
       return type_ < host_id.type();
     else if (id_ != host_id.id())
       return id_ < host_id.id();
     return false;
   }
 
+  bool operator==(const HostID& host_id) const {
+    return type_ == host_id.type() && id_ == host_id.id();
+  }
+
   HostType type() const { return type_; }
   const std::string& id() const { return id_; }
 
  private:
   // The type of the host.
   HostType type_;
 
   // Similar to extension_id, host_id is a unique indentifier for a host,
   // e.g., an Extension or WebUI.
   std::string id_;
 };
 
 #endif  // EXTENSIONS_COMMON_HOST_ID_H_