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

extensions/common/host_id.h

Index: extensions/common/host_id.h
diff --git a/extensions/common/host_id.h b/extensions/common/host_id.h
index 004480704f07766662006c7c3c570883c7e9a296..7efd64d67559c158ac2133dd3ed4797146fd8e17 100644
--- a/extensions/common/host_id.h
+++ b/extensions/common/host_id.h
@@ -7,6 +7,8 @@
 
 #include <string>
 
+#include "base/macros.h"
+
 // IDs of hosts who own user scripts.
 // A HostID is immutable after creation.
 struct HostID {
@@ -15,6 +17,9 @@ struct HostID {
   HostID() {}
   HostID(HostType type, const std::string& id)
       : type_(type), id_(id) {}
+  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())
@@ -36,4 +41,24 @@ struct HostID {
   std::string id_;
 };
 
+// An interface for all kinds of  hosts who own user scripts.

[Devlin, 2015/02/04 17:01:14]

nit: extra space between "of" and "hosts"

[Xi Han, 2015/02/05 16:06:20]

Done.

+class Host {
+ public:
+  // 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;
+
+  Host(const HostID& host_id);
+  virtual ~Host();
+
+  const HostID& id() const { return id_; }
+ private:
+  // The ID of the host.
+  HostID id_;
+
+  DISALLOW_COPY_AND_ASSIGN(Host);
+};
+
 #endif  // EXTENSIONS_COMMON_HOST_ID_H_