Hint talkback to tell if results were in the password search

Currently, talkback only announces when the search results change.
If all elements are filtered, there will be no feedback. This changes
with this CL and talkback will announce "No Results".

Bug: 820202
Change-Id: I73133cfe77a1e5a7a1847212e3c582c52e395b20
Reviewed-on: https://chromium-review.googlesource.com/958905Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543373}

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferences.java

@@ -759,6 +759,9 @@ public class SavePasswordsPreferences
             if (mSearchQuery == null) {
                 // If not searching, the category needs to be removed again.
                 getPreferenceScreen().removePreference(passwordParent);
+            } else {
+                getView().announceForAccessibility(
+                        getResources().getText(R.string.accessible_find_in_page_no_results));
             }
         }
     }