Take 2 at implementing activeTab.

chrome/renderer/extensions/user_script_slave.cc

Index: chrome/renderer/extensions/user_script_slave.cc
diff --git a/chrome/renderer/extensions/user_script_slave.cc b/chrome/renderer/extensions/user_script_slave.cc
index 8862631a2c47999dce84d3bfa23ce8a16df30db2..f1f752aaea5f7dc855db5ce4e70d8e85502fdf4c 100644
--- a/chrome/renderer/extensions/user_script_slave.cc
+++ b/chrome/renderer/extensions/user_script_slave.cc
@@ -279,8 +279,17 @@ void UserScriptSlave::InjectScripts(WebFrame* frame,
     if (!extension)
       continue;
 
-    if (!extension->CanExecuteScriptOnPage(data_source_url, script, NULL))
+    // Don't consider the tab ID when deciding whether to run content scripts;

[Aaron Boodman, 2012/06/06 01:03:13]

I think this comment can just be:

// Content scripts are not tab-specific.

[not at google - send to devlin, 2012/06/06 07:38:40]

Done.

[not at google - send to devlin, 2012/06/06 07:38:40]

Done.

+    // they may be targeted at a specific site, so allowing them to run based
+    // on the tab would be wrong.
+    int no_tab_id = -1;
+
+    if (!extension->CanExecuteScriptOnPage(data_source_url,
+                                           no_tab_id,
+                                           script,
+                                           NULL)) {
       continue;
+    }
 
     // We rely on WebCore for CSS injection, but it's still useful to know how
     // many css files there are.