Make GreasemonkeyApiJsString truly singleton.

extensions/renderer/user_script_injector.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/user_script_injector.h"
 
 #include <tuple>
 #include <vector>
 
 #include "base/lazy_instance.h"
@@ skipping 47 matching lines @@
 // |script_id| and |routing_id| pair.
 base::LazyInstance<RoutingInfoMap> g_routing_info_map =
     LAZY_INSTANCE_INITIALIZER;
 
 // Greasemonkey API source that is injected with the scripts.
 struct GreasemonkeyApiJsString {
   GreasemonkeyApiJsString();
   blink::WebScriptSource GetSource() const;
 
  private:
-  std::string source_;
+  // Data is owned by ResourceBundle.

[Devlin, 2016/08/20 01:58:36]

Not quite true, right? fromUTF8() still performs a copy of the data and makes a
refcounted storage (so this initial copy is the only one), but the data will be
owned by WebString storage.

So I would just omit this comment entirely.

[lazyboy, 2016/08/22 17:09:50]

That's right. Removed the comment.
 fromUTF8() still performs a copy of the data and makes a

+  blink::WebString source_;
 };
 
 // The below constructor, monstrous as it is, just makes a WebScriptSource from
 // the GreasemonkeyApiJs resource.
-GreasemonkeyApiJsString::GreasemonkeyApiJsString()
-    : source_(ResourceBundle::GetSharedInstance()
-                  .GetRawDataResource(IDR_GREASEMONKEY_API_JS)
-                  .as_string()) {
+GreasemonkeyApiJsString::GreasemonkeyApiJsString() {
+  base::StringPiece source_piece =
+      ResourceBundle::GetSharedInstance().GetRawDataResource(
+          IDR_GREASEMONKEY_API_JS);
+  source_ =
+      blink::WebString::fromUTF8(source_piece.data(), source_piece.length());
 }
 
 blink::WebScriptSource GreasemonkeyApiJsString::GetSource() const {
-  return blink::WebScriptSource(blink::WebString::fromUTF8(source_));
+  return blink::WebScriptSource(source_);
 }
 
 base::LazyInstance<GreasemonkeyApiJsString> g_greasemonkey_api =
     LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 UserScriptInjector::UserScriptInjector(const UserScript* script,
                                        UserScriptSet* script_list,
                                        bool is_declarative)
@@ skipping 191 matching lines @@
 void UserScriptInjector::OnInjectionComplete(
     std::unique_ptr<base::Value> execution_result,
     UserScript::RunLocation run_location,
     content::RenderFrame* render_frame) {}
 
 void UserScriptInjector::OnWillNotInject(InjectFailureReason reason,
                                          content::RenderFrame* render_frame) {
 }
 
 }  // namespace extensions