ContextualSearchObserver is now package protected

This patch makes ContextualSearchObserver package protected since its
use is specific to the feature itself.

Bug: 878006
Change-Id: If2e2a660199baf4600caf28729e7b2af3f41d8a1
Reviewed-on: https://chromium-review.googlesource.com/1198005Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588169}

chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java

@@ -916,13 +916,13 @@ public class ContextualSearchManager
     // ============================================================================================
 
     /** @param observer An observer to notify when the user performs a contextual search. */
-    public void addObserver(ContextualSearchObserver observer) {
+    void addObserver(ContextualSearchObserver observer) {
         mObservers.addObserver(observer);
     }
 
     /** @param observer An observer to no longer notify when the user performs a contextual search.
      */
-    public void removeObserver(ContextualSearchObserver observer) {
+    void removeObserver(ContextualSearchObserver observer) {
         mObservers.removeObserver(observer);
     }
 

chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchObserver.java

@@ -11,7 +11,7 @@ import javax.annotation.Nullable;
 /**
  * An interface to be notified when contextual searches are performed or no longer active.
  */
-public interface ContextualSearchObserver {
+interface ContextualSearchObserver {
     /**
      * Notifies that a contextual search was performed, and provides the selection context if
      * the feature is fully enabled (and {@code null} otherwise).