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 cc574d97f8424b1337a5b9da04e8c422b252dfb8..3422fb16b8f2024061e31fa2c686f4d5649c5ddf 100644
--- a/extensions/common/manifest_constants.cc
+++ b/extensions/common/manifest_constants.cc
@@ -75,6 +75,7 @@ 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";
@@ -478,6 +479,8 @@ 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.";