Stop copying script contents for each RenderFrames.

extensions/renderer/user_script_injector.cc

Index: extensions/renderer/user_script_injector.cc
diff --git a/extensions/renderer/user_script_injector.cc b/extensions/renderer/user_script_injector.cc
index da0c760e54425c7c329438150ed892501b18c6d5..6d3c857227a143e6a040d70617da47c3bd5507d6 100644
--- a/extensions/renderer/user_script_injector.cc
+++ b/extensions/renderer/user_script_injector.cc
@@ -18,11 +18,9 @@
 #include "extensions/renderer/injection_host.h"
 #include "extensions/renderer/script_context.h"
 #include "extensions/renderer/scripts_run_info.h"
-#include "grit/extensions_renderer_resources.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
 #include "third_party/WebKit/public/web/WebScriptSource.h"
-#include "ui/base/resource/resource_bundle.h"
 #include "url/gurl.h"
 
 namespace extensions {
@@ -44,11 +42,6 @@ struct RoutingInfoKey {
 
 using RoutingInfoMap = std::map<RoutingInfoKey, bool>;
 
-// These two strings are injected before and after the Greasemonkey API and
-// user script to wrap it in an anonymous scope.
-const char kUserScriptHead[] = "(function (unsafeWindow) {\n";
-const char kUserScriptTail[] = "\n})(window);";
-
 // A map records whether a given |script_id| from a webview-added user script
 // is allowed to inject on the render of given |routing_id|.
 // Once a script is added, the decision of whether or not allowed to inject
@@ -59,38 +52,13 @@ const char kUserScriptTail[] = "\n})(window);";
 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:
-  blink::WebString source_;
-};
-
-// The below constructor, monstrous as it is, just makes a WebScriptSource from
-// the GreasemonkeyApiJs resource.
-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(source_);
-}
-
-base::LazyInstance<GreasemonkeyApiJsString> g_greasemonkey_api =
-    LAZY_INSTANCE_INITIALIZER;
-
 }  // namespace
 
 UserScriptInjector::UserScriptInjector(const UserScript* script,
                                        UserScriptSet* script_list,
                                        bool is_declarative)
     : script_(script),
+      user_script_set_(script_list),
       script_id_(script_->id()),
       host_id_(script_->host_id()),
       is_declarative_(is_declarative),
@@ -203,60 +171,17 @@ std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
     return sources;
 
   DCHECK_EQ(script_->run_location(), run_location);
-
-  const UserScript::FileList& js_scripts = script_->js_scripts();
-  sources.reserve(js_scripts.size());
-  for (const std::unique_ptr<UserScript::File>& file : js_scripts) {
-    base::StringPiece script_content = file->GetContent();
-    blink::WebString source;
-    if (script_->emulate_greasemonkey()) {
-      // We add this dumb function wrapper for user scripts to emulate what
-      // Greasemonkey does. |script_content| becomes:
-      // concat(kUserScriptHead, script_content, kUserScriptTail).
-      std::string content;
-      content.reserve(strlen(kUserScriptHead) + script_content.length() +
-                      strlen(kUserScriptTail));
-      content.append(kUserScriptHead);
-      script_content.AppendToString(&content);
-      content.append(kUserScriptTail);
-      // TODO(lazyboy): |content| is copied to |source|, should be avoided.
-      // Investigate if we can leverage WebString's cheap copying mechanism
-      // somehow.
-      source = blink::WebString::fromUTF8(content);
-    } else {
-      source = blink::WebString::fromUTF8(script_content.data(),
-                                          script_content.length());
-    }
-    sources.push_back(blink::WebScriptSource(source, file->url()));
-  }
-
-  // Emulate Greasemonkey API for scripts that were converted to extension
-  // user scripts.
-  if (script_->emulate_greasemonkey())
-    sources.insert(sources.begin(), g_greasemonkey_api.Get().GetSource());
-
-  return sources;
+  return user_script_set_->GetJsSources(script_->id());
 }
 
 std::vector<blink::WebString> UserScriptInjector::GetCssSources(
     UserScript::RunLocation run_location) const {
   DCHECK_EQ(UserScript::DOCUMENT_START, run_location);
 
-  std::vector<blink::WebString> sources;
   if (!script_)
-    return sources;
+    return std::vector<blink::WebString>();
 
-  const UserScript::FileList& css_scripts = script_->css_scripts();
-  sources.reserve(css_scripts.size());
-  for (const std::unique_ptr<UserScript::File>& file : script_->css_scripts()) {
-    // TODO(lazyboy): |css_content| string is copied into blink::WebString for
-    // every frame in the current renderer process. Avoid the copy, possibly by
-    // only performing the copy once.
-    base::StringPiece css_content = file->GetContent();
-    sources.push_back(
-        blink::WebString::fromUTF8(css_content.data(), css_content.length()));
-  }
-  return sources;
+  return user_script_set_->GetCssSources(script_->id());
 }
 
 void UserScriptInjector::GetRunInfo(