Cleanup: Remove unused variables in chrome/ found by Scythe.

chrome/renderer/extensions/chrome_v8_extension_handler.h

Index: chrome/renderer/extensions/chrome_v8_extension_handler.h
diff --git a/chrome/renderer/extensions/chrome_v8_extension_handler.h b/chrome/renderer/extensions/chrome_v8_extension_handler.h
index 4802d839881768b146d3527e5c13781e69f7b042..b2a1572f08e0be67b08e93c47e9125619ab10880 100644
--- a/chrome/renderer/extensions/chrome_v8_extension_handler.h
+++ b/chrome/renderer/extensions/chrome_v8_extension_handler.h
@@ -12,7 +12,6 @@
 #include "v8/include/v8.h"
 
 namespace extensions {
-class ScriptContext;
 
 // Base class for context-scoped handlers used with ChromeV8Extension.
 // TODO(koz): Rename/refactor this somehow. Maybe just pull it into
@@ -25,10 +24,9 @@ class ChromeV8ExtensionHandler : public IPC::Listener {
   bool OnMessageReceived(const IPC::Message& message) override = 0;
 
  protected:
-  explicit ChromeV8ExtensionHandler(ScriptContext* context);
+  ChromeV8ExtensionHandler();
   int GetRoutingID();
   void Send(IPC::Message* message);
-  ScriptContext* context_;
 
  private:
   int routing_id_;