[Android Bookmarks] Hide search view when system back is pressed

chrome/android/java/src/org/chromium/chrome/browser/bookmarks/BookmarkManager.java

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.bookmarks;
 
 import android.app.Activity;
 import android.app.ActivityManager;
 import android.content.Context;
 import android.support.graphics.drawable.VectorDrawableCompat;
@@ skipping 197 matching lines @@
      * Called when the user presses the back key. This is only going to be called on Phone.
      * @return True if manager handles this event, false if it decides to ignore.
      */
     public boolean onBackPressed() {
         // TODO(twellington): replicate this behavior for other list UIs during unification.
         if (mSelectionDelegate.isSelectionEnabled()) {
             mSelectionDelegate.clearSelection();
             return true;
         }
 
+        if (mToolbar.isSearching()) {
+            mToolbar.hideSearchView();
+            return true;
+        }
+
         if (!mStateStack.empty()) {
             mStateStack.pop();
             if (!mStateStack.empty()) {
                 setState(mStateStack.pop());
                 return true;
             }
         }
         return false;
     }
 
@@ skipping 218 matching lines @@
         closeSearchUI();
     }
 
     // Testing methods
 
     @VisibleForTesting
     public BookmarkActionBar getToolbarForTests() {
         return mToolbar;
     }
 }