Added code to dismiss url suggestion popup on back key press.

chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.java

 // Copyright 2014 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.shell;
 
 import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.drawable.ClipDrawable;
 import android.util.AttributeSet;
@@ skipping 122 matching lines @@
         mUrlTextView.setOnFocusChangeListener(new OnFocusChangeListener() {
             @Override
             public void onFocusChange(View v, boolean hasFocus) {
                 setKeyboardVisibilityForUrl(hasFocus);
                 if (!hasFocus) {
                     mUrlTextView.setText(mTab.getContentViewCore().getUrl());
                     mSuggestionPopup.dismissPopup();
                 }
             }
         });
+        mUrlTextView.setOnKeyListener(new OnKeyListener() {
+            @Override
+            public boolean onKey(View v, int keyCode, KeyEvent event) {
+                if (keyCode == KeyEvent.KEYCODE_BACK) {
+                    mUrlTextView.clearFocus();
+                    if (mTab != null) {
+                        mTab.getView().requestFocus();
+                    }
+                    return true;
+                }
+                return false;
+            }
+        });
 
         mSuggestionPopup = new SuggestionPopup(getContext(), mUrlTextView, this);
         mUrlTextView.addTextChangedListener(mSuggestionPopup);
     }
 
     private void initializeMenuButton() {
         ImageButton menuButton = (ImageButton) findViewById(R.id.menu_button);
         menuButton.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View view) {
@@ skipping 40 matching lines @@
         public void onLoadProgressChanged(Tab tab, int progress) {
             if (tab == mTab) ChromeShellToolbar.this.onLoadProgressChanged(progress);
         }
 
         @Override
         public void onUpdateUrl(Tab tab, String url) {
             if (tab == mTab) ChromeShellToolbar.this.onUpdateUrl(url);
         }
     }
 }