Allow content script insertion on about:-URLs.

extensions/common/manifest_constants.cc

Index: extensions/common/manifest_constants.cc
diff --git a/extensions/common/manifest_constants.cc b/extensions/common/manifest_constants.cc
index e0433b3b00e6ca2a7d6020df8a4c672b3f08dd60..a1e5131998cd3a4324aff4859042ab170e64e9f3 100644
--- a/extensions/common/manifest_constants.cc
+++ b/extensions/common/manifest_constants.cc
@@ -74,6 +74,7 @@ const char kLaunchWebURL[] = "app.launch.web_url";
 const char kLaunchWidth[] = "app.launch.width";
 const char kLayouts[] = "layouts";
 const char kManifestVersion[] = "manifest_version";
+const char kMatchAboutBlank[] = "match_about_blank";
 const char kMatches[] = "matches";
 const char kMinimumChromeVersion[] = "minimum_chrome_version";
 const char kMinimumVersion[] = "minimum_version";
@@ -472,6 +473,8 @@ const char kInvalidManifestVersionOld[] =
     "See developer.chrome.com/*/manifestVersion.html for details.";
 const char kInvalidMatch[] =
     "Invalid value for 'content_scripts[*].matches[*]': *";
+const char kInvalidMatchAboutBlank[] =
+    "Invalid value for 'content_scripts[*].match_about_blank'.";
 const char kInvalidMatchCount[] =
     "Invalid value for 'content_scripts[*].matches'. There must be at least "
     "one match specified.";