Refactoring: de-couple Extensions from "script injection System" [render side]:3

extensions/renderer/script_injection.h

Index: extensions/renderer/script_injection.h
diff --git a/extensions/renderer/script_injection.h b/extensions/renderer/script_injection.h
index 6c265894e145f3eb1577a3f3d8de0f3b20b3090c..a55c6e645949beaac5355abfb7046e205dbef096 100644
--- a/extensions/renderer/script_injection.h
+++ b/extensions/renderer/script_injection.h
@@ -8,9 +8,9 @@
 #include "base/basictypes.h"
 #include "base/macros.h"
 #include "extensions/common/user_script.h"
+#include "extensions/renderer/injection_host.h"
 #include "extensions/renderer/script_injector.h"
 
-class InjectionHost;
 struct HostID;
 
 namespace blink {
@@ -33,7 +33,7 @@ class ScriptInjection {
   ScriptInjection(
       scoped_ptr<ScriptInjector> injector,
       blink::WebLocalFrame* web_frame,
-      const HostID& host_id,
+      scoped_ptr<const InjectionHost> injection_host,
       const UserScript::ConsumerInstanceType& consumer_instance_type,
       UserScript::RunLocation run_location,
       int tab_id);
@@ -53,9 +53,14 @@ class ScriptInjection {
   bool OnPermissionGranted(const InjectionHost* injection_host,
                            ScriptsRunInfo* scripts_run_info);
 
+  // Gets the associated injection host. If the host is an extension, we check
+  // whether the extension exists first; and if the extension is gone, will
+  // return a nullptr.
+  const InjectionHost* GetInjectionHost();
+
   // Accessors.
   blink::WebLocalFrame* web_frame() const { return web_frame_; }
-  const HostID& host_id() const { return host_id_; }
+  const HostID& host_id() const { return injection_host_->id(); }
   int64 request_id() const { return request_id_; }
 
  private:
@@ -84,8 +89,8 @@ class ScriptInjection {
   // The (main) WebFrame into which this should inject the script.
   blink::WebLocalFrame* web_frame_;
 
-  // The id of the associated injection_host.
-  HostID host_id_;
+  // The associated injection host.
+  scoped_ptr<const InjectionHost> injection_host_;
 
   // The type of the instance on which the host will inject the script.
   UserScript::ConsumerInstanceType consumer_instance_type_;