Update the DataSaver off page strings

With the advent of HTTPS Server Previews, we need to remove the "not
HTTPS" verbage from these strings. See the bug for more info and where
I got the strings.

Bug: 889684
Change-Id: I6d3669f30415396a68b81e316a9cc3435fc33f37
Reviewed-on: https://chromium-review.googlesource.com/1255682Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595726}

chrome/android/java/res/xml/data_reduction_preferences_off.xml

@@ -6,6 +6,8 @@
 <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
                   xmlns:app="http://schemas.android.com/apk/res-auto" >
 
+    <org.chromium.chrome.browser.preferences.TextMessagePreference
+        android:title="@string/data_reduction_benefits_description" />
     <org.chromium.chrome.browser.preferences.TextMessagePreference
         android:title="@string/data_reduction_description" />
     <org.chromium.chrome.browser.preferences.TextMessagePreference

chrome/android/java/strings/android_chrome_strings.grd

@@ -1226,8 +1226,11 @@ To obtain new licenses, connect to the internet and play your downloaded content
       <message name="IDS_DATA_REDUCTION_DATE_LABEL" desc="Summary text for the menu item that states the beginning date when the displayed mobile data was saved (i.e. XX MB saved 'since Feb 28')">
         since <ph name="date">%1$s<ex>Feb 28</ex></ph>
       </message>
-      <message name="IDS_DATA_REDUCTION_DESCRIPTION" desc="Description text for the Data Saver feature.">
-        When this feature is turned on, Chrome will use Google servers to compress pages you visit before downloading them. Pages accessed using private connections (HTTPS) or in Incognito tabs will not be optimized or seen by Google.
+      <message name="IDS_DATA_REDUCTION_BENEFITS_DESCRIPTION" desc="Description text about the benefits of the Data Saver feature. Seen only before the user has enabled the feature.">
+        Use up to 60% less data and speed up the web.
+      </message>
+      <message name="IDS_DATA_REDUCTION_DESCRIPTION" desc="Text descripting how the Data Saver feature works. Seen only before the user has enabled the feature.">
+        When Data Saver is turned on, Chrome uses Google servers to speed up and compress page loads. On especially slow pages, Data Saver rewrites the page to load only the essential content. Data Saver does not optimize pages loaded in Incognito mode.
       </message>
       <message name="IDS_DATA_REDUCTION_MENU_ITEM_SUMMARY" desc="Summary text for data reduction menu item.">
         <ph name="PERCENT">%1$s<ex>49%</ex></ph> data savings