Prevent duplicate content script injection defined in manifest.json

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 1910548ba24b340d720cd7eb4ea16d8af38e6416..f653cf4b792327763d2609181802f725bad47bcb 100644
--- a/extensions/renderer/user_script_injector.cc
+++ b/extensions/renderer/user_script_injector.cc
@@ -197,7 +197,8 @@ PermissionsData::AccessType UserScriptInjector::CanExecuteOnFrame(
 }
 
 std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
-    UserScript::RunLocation run_location) const {
+    UserScript::RunLocation run_location,
+    ScriptsRunInfo* scripts_run_info) const {
   std::vector<blink::WebScriptSource> sources;
   if (!script_)
     return sources;
@@ -209,6 +210,11 @@ std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
   for (UserScript::FileList::const_iterator iter = js_scripts.begin();
        iter != js_scripts.end();
        ++iter) {
+    const GURL& script_url = iter->url();
+    // Check if the script is already injected.
+    if (scripts_run_info->injected_scripts.count(script_url) != 0)
+      continue;
+
     std::string content = iter->GetContent().as_string();
 
     // We add this dumb function wrapper for user scripts to emulate what
@@ -218,7 +224,9 @@ std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
       content += kUserScriptTail;
     }
     sources.push_back(blink::WebScriptSource(
-        blink::WebString::fromUTF8(content), iter->url()));
+        blink::WebString::fromUTF8(content), script_url));
+
+    scripts_run_info->injected_scripts.insert(script_url);
   }
 
   // Emulate Greasemonkey API for scripts that were converted to extension
@@ -230,7 +238,8 @@ std::vector<blink::WebScriptSource> UserScriptInjector::GetJsSources(
 }
 
 std::vector<std::string> UserScriptInjector::GetCssSources(
-    UserScript::RunLocation run_location) const {
+    UserScript::RunLocation run_location,
+    ScriptsRunInfo* scripts_run_info) const {
   DCHECK_EQ(UserScript::DOCUMENT_START, run_location);
 
   std::vector<std::string> sources;
@@ -238,10 +247,18 @@ std::vector<std::string> UserScriptInjector::GetCssSources(
     return sources;
 
   const UserScript::FileList& css_scripts = script_->css_scripts();
+
   for (UserScript::FileList::const_iterator iter = css_scripts.begin();
        iter != css_scripts.end();
        ++iter) {
-    sources.push_back(iter->GetContent().as_string());
+    const GURL& script_url = iter->url();
+    // Check if the stylesheet is already injected.
+    if (scripts_run_info->injected_scripts.find(script_url) ==
+        scripts_run_info->injected_scripts.end()) {
+      sources.push_back(iter->GetContent().as_string());
+
+      scripts_run_info->injected_scripts.insert(script_url);
+    }
   }
   return sources;
 }