Update NTP Fakebox hint text for GM2

Change the hint text shown in the NTP fakebox for GM2.

Bug: 837784
Change-Id: I42d74283515ac575418e49d88fbcd7be1702702f
Reviewed-on: https://chromium-review.googlesource.com/1042268Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556788}

chrome/app/generated_resources.grd

@@ -4889,6 +4889,9 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT" desc="The text displayed in the fakebox (on the New Tab page) when it is empty, and Google is the default search engine.">
         Search Google or type URL
       </message>
+      <message name="IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT_MD" desc="The text displayed in the fakebox (on the New Tab page) when it is empty, Google is the default search engine, and the MD UI is enabled.">
+        Search Google or type a web address
+      </message>
       <message name="IDS_CLICK_TO_VIEW_DOODLE" desc="Prompts users to click on an icon to view a Google doodle. Normally, today's Google doodle is shown when the user opens a new tab (if there is a doodle today). If there is a doodle, but it cannot be shown, Chrome puts an icon next to the regular Google logo. The icon uses this label for accessibility. If the user clicks the icon, Chrome will show the doodle.">
         Click to view today’s doodle
       </message>

chrome/app/generated_resources_grd/IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT_MD.png.sha1

+bc84d73368bcadc3aeacdc86226f0fa28c9af101
\ No newline at end of file

chrome/app/generated_resources_grd/OWNERS

+# COMPONENT: Internals>PlatformIntegration
+#
+# Any Chromium committer can approve changes to generated_resources.grd,
+# so they are also allowed to approve the corresponding sha1 hashes
+# for string translation.
+
+per-file *.png.sha1=*

chrome/browser/search/local_ntp_source.cc

@@ -125,7 +125,9 @@ std::unique_ptr<base::DictionaryValue> GetTranslatedStrings(bool is_google) {
 
   if (is_google) {
     AddString(translated_strings.get(), "searchboxPlaceholder",
-              IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT);
+              base::FeatureList::IsEnabled(features::kNtpUIMd)
+                  ? IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT_MD
+                  : IDS_GOOGLE_SEARCH_BOX_EMPTY_HINT);
 
     // Voice Search
     AddString(translated_strings.get(), "audioError",