Make ModuleSystem have a const view of ResourceBundleSourceMap.

extensions/renderer/resource_bundle_source_map.h

Index: extensions/renderer/resource_bundle_source_map.h
diff --git a/extensions/renderer/resource_bundle_source_map.h b/extensions/renderer/resource_bundle_source_map.h
index 13f8f216697cc4bfc1f619cdcfdfcf67432a072d..9b7fd70737a7f1e0f7d26998a8921ce1485b908f 100644
--- a/extensions/renderer/resource_bundle_source_map.h
+++ b/extensions/renderer/resource_bundle_source_map.h
@@ -10,9 +10,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/memory/linked_ptr.h"
-#include "base/strings/string_piece.h"
 #include "extensions/renderer/module_system.h"
-#include "extensions/renderer/static_v8_external_one_byte_string_resource.h"
 #include "v8/include/v8.h"
 
 namespace ui {
@@ -27,17 +25,16 @@ class ResourceBundleSourceMap : public extensions::ModuleSystem::SourceMap {
   ~ResourceBundleSourceMap() override;
 
   v8::Local<v8::Value> GetSource(v8::Isolate* isolate,
-                                 const std::string& name) override;
-  bool Contains(const std::string& name) override;
+                                 const std::string& name) const override;
+  bool Contains(const std::string& name) const override;
 
   void RegisterSource(const std::string& name, int resource_id);
 
  private:
-  v8::Local<v8::String> ConvertString(v8::Isolate* isolate,
-                                      const base::StringPiece& string);
-
   const ui::ResourceBundle* resource_bundle_;
   std::map<std::string, int> resource_id_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourceBundleSourceMap);
 };
 
 }  // namespace extensions