Fixed disabled status of Find-in-page previous/next arrows

Currently the previous/next arrows are not disabled when there is no
text match. Fixed this.

BUG=509857

Review-Url: https://codereview.chromium.org/2584983002
Cr-Commit-Position: refs/heads/master@{#439532}

chrome/android/java/src/org/chromium/chrome/browser/widget/findinpage/FindToolbar.java

@@ -235,7 +235,6 @@ public class FindToolbar extends LinearLayout
                 if (mFindInPageBridge == null) return;
 
                 mAccessibilityDidActivateResult = false;
-                setPrevNextEnabled(s.length() > 0);
 
                 if (mSettingFindTextProgrammatically) return;
 
@@ -430,6 +429,8 @@ public class FindToolbar extends LinearLayout
                 result.numberOfMatches);
         setStatus(text, result.numberOfMatches == 0);
 
+        setPrevNextEnabled(result.numberOfMatches > 0);
+
         // The accessible version will be something like "Result 1 of 9".
         String accessibleText = getAccessibleStatusText(
                 Math.max(result.activeMatchOrdinal, 0),