Add a Rappor option in the settings page.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index e99ff174fd67456b52174f0c206aac84124de7ee..0e3f2284f1322612fadf0fc2b57cf32d1d7faaea 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -12156,6 +12156,9 @@ The following application will be launched if you accept this request:
       <message name="IDS_OPTIONS_ENABLE_LOGGING" desc="The label of the checkbox to enable/disable crash and user metrics logging">
         Automatically send usage statistics and crash reports to Google
       </message>
+      <message name="IDS_OPTIONS_ENABLE_RAPPOR" desc="The label of the checkbox to enable/disable rappor metrics logging">
+        Send <ph name="BEGIN_LINK">&lt;a target="_blank" href="$1"&gt;</ph>RAPPOR<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph> statistics to Google

[Thiemo Nagel, 2015/02/11 10:50:51]

nit: how about inserting "anonymous" here?

[Steven Holte, 2015/02/11 20:03:32]

This was discussed by hodie, battre and others, but it was decided against,
partly because we don't want to imply that other metrics like crash uploads
aren't anonymous.

+      </message>
       <message name="IDS_OPTIONS_ENABLE_LOGGING_RESTART" desc="The restart string after changing crash and user metrics logging. The text within the | symbols will be made into a link that should indicate to the user that clicking on it will cause Chrome to restart.">
         (requires Chrome |restart|)
       </message>