Clarify wording around blocking 3rd party cookies and add lab to block reading of 3rd party cookies

BUG=69066
TEST=net_unittests

Review URL: http://codereview.chromium.org/6207005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71148 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 9caa41c..44ac3e4 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -273,6 +273,13 @@
     kOsWin | kOsLinux,
     SINGLE_VALUE_TYPE(switches::kInstantAutocompleteImmediately)
   },
+  {
+    "block-reading-third-party-cookies",
+    IDS_FLAGS_BLOCK_ALL_THIRD_PARTY_COOKIES_NAME,
+    IDS_FLAGS_BLOCK_ALL_THIRD_PARTY_COOKIES_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(switches::kBlockReadingThirdPartyCookies)
+  },
 };
 
 const Experiment* experiments = kExperiments;