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

chrome/browser/extensions/api/declarative_content/content_action.h

Index: chrome/browser/extensions/api/declarative_content/content_action.h
diff --git a/chrome/browser/extensions/api/declarative_content/content_action.h b/chrome/browser/extensions/api/declarative_content/content_action.h
index dc39431aed870bfe65d677064bf23bc30e542a05..67ee47923d27700317730bb9d81211cbd47e964c 100644
--- a/chrome/browser/extensions/api/declarative_content/content_action.h
+++ b/chrome/browser/extensions/api/declarative_content/content_action.h
@@ -95,6 +95,15 @@ class RequestContentScript : public ContentAction {
  public:
   struct ScriptData;
 
+  // TODO(hanxi): add RulesRegistryID to the RequestKey.
+  struct RequestKey {

[Devlin, 2015/01/20 17:51:05]

Could we instead just use a std::string for this?

[Xi Han, 2015/01/21 21:30:16]

Ok, I will change it to std::string, and change it when we need to include more
information for <webview>.

+    explicit RequestKey(const std::string& host_id) : host_id(host_id) {}
+    bool operator<(const RequestKey& key) const {
+      return host_id.compare(key.host_id) < 0;
+    }
+    std::string host_id;
+  };
+
   RequestContentScript(content::BrowserContext* browser_context,
                        const Extension* extension,
                        const ScriptData& script_data);
@@ -150,6 +159,8 @@ class RequestContentScript : public ContentAction {
                                      const std::string& extension_id) const;
 
   UserScript script_;
+  // The lifetime of the master_ is managed by DeclarativeUserScriptManager,

[Devlin, 2015/01/20 17:51:05]

nit: newline before this.
nit: Document why the lifetime is safe (i.e., show that the
DeclarativeUserScriptManager outlives the RequestContentScript).

[Xi Han, 2015/01/21 21:30:16]

Lifetime is hard to explain, so I try my best to add some comments here. Feel
free to update if you think they are not enough to explain. Thanks.

+  // which manages a map of master objects.
   DeclarativeUserScriptMaster* master_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestContentScript);