Allow content script insertion on about:-URLs.

chrome/common/extensions/api/tabs.json

Index: chrome/common/extensions/api/tabs.json
diff --git a/chrome/common/extensions/api/tabs.json b/chrome/common/extensions/api/tabs.json
index 879c1b84efcdda8f9beb4c6f0fc0e772c79e9bf7..e725cf03dffb490316ee824668381f5486363ee3 100644
--- a/chrome/common/extensions/api/tabs.json
+++ b/chrome/common/extensions/api/tabs.json
@@ -38,6 +38,7 @@
           "code": {"type": "string", "optional": true, "description": "JavaScript or CSS code to inject.<br><br><b>Warning:</b><br>Be careful using the <code>code</code> parameter. Incorrect use of it may open your extension to <a href=\"https://en.wikipedia.org/wiki/Cross-site_scripting\">cross site scripting</a> attacks."},
           "file": {"type": "string", "optional": true, "description": "JavaScript or CSS file to inject."},
           "allFrames": {"type": "boolean", "optional": true, "description": "If allFrames is <code>true</code>, implies that the JavaScript or CSS should be injected into all frames of current page. By default, it's <code>false</code> and is only injected into the top frame."},
+          "matchAboutBlank": {"type": "boolean", "optional": true, "description": "If matchAboutBlank is true, then the code is also injected in about:blank and about:srcdoc frames if your extension has access to its parent document. Code cannot be inserted in top-level about:-frames. By default it is <code>false</code>."},
           "runAt": {
             "type": "string",
             "optional": true,