implemented snackbar - UNDO on closing tab

https://sourceforge.net/p/kiwix/feature-requests/232/

build.gradle

@@ -23,6 +23,7 @@ dependencies {
   compile 'com.android.support:support-v4:22.2.0'
   compile files("$buildDir/native-libs/native-libs.jar")
   compile 'com.yahoo.squidb:squidb:2.0.0'
+  compile 'com.android.support:design:22.2.0'
   compile 'com.yahoo.squidb:squidb-annotations:2.0.0'
   apt 'com.yahoo.squidb:squidb-processor:2.0.0'
   // compile fileTree(dir: '.', include: 'content-libs.jar') // DO NOT REMOVE !!

res/layout/main.xml

@@ -2,7 +2,8 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:orientation="vertical">
+    android:orientation="vertical"
+    android:id="@+id/linearlayout_main">
 
   <include layout="@layout/toolbar"/>
 

res/values/colors.xml

@@ -8,7 +8,7 @@
   <color name="secondary_text">#727272</color>
   <color name="icons">#212121</color>
   <color name="divider">#B6B6B6</color>
-
+  <color name="white_undo">#FAFAFA</color>
   <color name="gray_list_bg">#0d000000</color>
   <color name="drawer_background">#ffffff</color>
   <color name="selected_light">#0F000000</color>

src/org/kiwix/kiwixmobile/KiwixMobileActivity.java

@@ -32,6 +32,7 @@ import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
 import android.preference.PreferenceManager;
+import android.support.design.widget.Snackbar;
 import android.support.v4.view.GravityCompat;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.app.ActionBarDrawerToggle;
@@ -63,10 +64,12 @@ import android.widget.Button;
 import android.widget.FrameLayout;
 import android.widget.ImageButton;
 import android.widget.ImageView;
+import android.widget.LinearLayout;
 import android.widget.ListView;
 import android.widget.RelativeLayout;
 import android.widget.TextView;
 import android.widget.Toast;
+
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -78,6 +81,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
+
 import org.json.JSONArray;
 import org.kiwix.kiwixmobile.settings.Constants;
 import org.kiwix.kiwixmobile.settings.KiwixSettingsActivity;
@@ -169,6 +173,8 @@ public class KiwixMobileActivity extends AppCompatActivity
 
     // Initialized when onActionModeStarted is triggered.
     private ActionMode mActionMode = null;
+    private KiwixWebView tempForUndo;
+    private LinearLayout snackbarLayout;
 
     @Override
     public void onActionModeStarted(ActionMode mode) {
@@ -229,7 +235,9 @@ public class KiwixMobileActivity extends AppCompatActivity
         mToolbarContainer = (RelativeLayout) findViewById(R.id.toolbar_layout);
         mProgressBar = (AnimatedProgressBar) findViewById(R.id.progress_view);
         exitFullscreenButton = (ImageButton) findViewById(R.id.FullscreenControlButton);
+        tempForUndo = new KiwixWebView(getApplicationContext());   /**  initializing temporary tab value **/
 
+        snackbarLayout = (LinearLayout) findViewById(R.id.linearlayout_main);  /** Coordinator layout definition**/
         RelativeLayout newTabButton = (RelativeLayout) findViewById(R.id.new_tab_button);
         newTabButton.setOnClickListener(new View.OnClickListener() {
 
@@ -372,7 +380,21 @@ public class KiwixMobileActivity extends AppCompatActivity
             if (mCurrentWebViewIndex == index) {
                 if (mCurrentWebViewIndex >= 1) {
                     selectTab(mCurrentWebViewIndex - 1);
+
+                    tempForUndo = mWebViews.get(index);
+
                     mWebViews.remove(index);
+                    Snackbar undoSnackbar = Snackbar.make(snackbarLayout, "Click to restore tab", Snackbar.LENGTH_LONG)
+                            .setAction("Undo", new View.OnClickListener() {
+                                @Override
+                                public void onClick(View v) {
+                                    newTab(tempForUndo.getUrl());
+                                }
+                            });
+                    undoSnackbar.setActionTextColor(getResources().getColor(R.color.white_undo));
+                    undoSnackbar.show();
+
+
                 } else {
                     selectTab(mCurrentWebViewIndex + 1);
                     mWebViews.remove(index);
@@ -1180,7 +1202,6 @@ public class KiwixMobileActivity extends AppCompatActivity
     }
 
 
-
     @Override
     public void onPause() {
         super.onPause();