Stop copying script contents for each RenderFrames.

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 26 matching lines @@
       : routing_id(routing_id), script_id(script_id) {}
 
   bool operator<(const RoutingInfoKey& other) const {
     return std::tie(routing_id, script_id) <
            std::tie(other.routing_id, other.script_id);
   }
 };
 
 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
 // won't be changed.
 // After removed by the webview, the user scipt will also be removed
 // from the render. Therefore, there won't be any query from the same
 // |script_id| and |routing_id| pair.
 base::LazyInstance<RoutingInfoMap> g_routing_info_map =
     LAZY_INSTANCE_INITIALIZER;
 
@@ skipping 22 matching lines @@
 
 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),
       user_script_set_observer_(this) {
   user_script_set_observer_.Add(script_list);
 }
 
 UserScriptInjector::~UserScriptInjector() {
 }
 
@@ skipping 95 matching lines @@
 
 std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
     UserScript::RunLocation run_location) const {
   std::vector<blink::WebScriptSource> sources;
   if (!script_)
     return sources;
 
   DCHECK_EQ(script_->run_location(), run_location);
 
   const UserScript::FileList& js_scripts = script_->js_scripts();
-  sources.reserve(js_scripts.size());
+  sources.reserve(js_scripts.size() +
+                  (script_->emulate_greasemonkey() ? 1 : 0));
   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()));
+    sources.push_back(blink::WebScriptSource(
+        user_script_set_->GetJsSource(*file, script_->emulate_greasemonkey()),
+        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());

[Devlin, 2016/09/07 14:29:45]

nit: unrelated, but maybe put this before adding all the js scripts so we don't
have to move them all?

[lazyboy, 2016/09/07 16:47:35]

Done.

 
   return sources;
 }
 
 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;
 
   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()));
-  }
+  for (const std::unique_ptr<UserScript::File>& file : script_->css_scripts())
+    sources.push_back(user_script_set_->GetCssSource(*file));
   return sources;
 }
 
 void UserScriptInjector::GetRunInfo(
     ScriptsRunInfo* scripts_run_info,
     UserScript::RunLocation run_location) const {
   if (!script_)
     return;
 
   if (ShouldInjectJs(run_location)) {
@@ skipping 12 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