Bug 1100464 - Add back button to top left of the tabs panel (r=lucasr)

mobile/android/base/newtablet/res/layout-large-v11/new_tablet_tabs_panel_back_button.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<ImageButton xmlns:android="http://schemas.android.com/apk/res/android"
+             android:id="@+id/nav_back"
+             android:layout_width="@dimen/tabs_panel_indicator_width"
+             android:layout_height="match_parent"
+             android:minWidth="@dimen/tabs_panel_indicator_width"
+             android:src="@drawable/new_tablet_nav_back"
+             android:contentDescription="@string/back"
+             android:background="@drawable/action_bar_button_inverse"/>
+

mobile/android/base/resources/layout/tabs_panel_default.xml

@@ -18,6 +18,11 @@
               android:layout_height="match_parent"
               android:background="@color/background_tabs">
 
+            <ViewStub android:id="@+id/nav_back_stub"
+                      android:layout="@layout/new_tablet_tabs_panel_back_button"
+                      android:layout_width="wrap_content"
+                      android:layout_height="match_parent"/>
+
             <org.mozilla.gecko.widget.IconTabWidget android:id="@+id/tab_widget"
                                                     android:layout_width="wrap_content"
                                                     android:layout_height="match_parent"

mobile/android/base/resources/values/layout.xml

@@ -9,4 +9,5 @@
     <item type="layout" name="new_tablet_browser_toolbar">@null</item>
     <item type="layout" name="new_tablet_tab_strip">@null</item>
     <item type="layout" name="new_tablet_tabs_item_cell">@null</item>
+    <item type="layout" name="new_tablet_tabs_panel_back_button">@null</item>
 </resources>

mobile/android/base/tabs/TabsPanel.java

@@ -30,6 +30,7 @@ import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.ViewStub;
 import android.widget.Button;
 import android.widget.FrameLayout;
 import android.widget.ImageButton;
@@ -88,6 +89,7 @@ public class TabsPanel extends LinearLayout
     private IconTabWidget mTabWidget;
     private static ImageButton mMenuButton;
     private static ImageButton mAddTab;
+    private ImageButton mNavBackButton;
 
     private Panel mCurrentPanel;
     private boolean mIsSideBar;
@@ -163,6 +165,17 @@ public class TabsPanel extends LinearLayout
                 showMenu();
             }
         });
+
+        if(NewTabletUI.isEnabled(getContext())) {
+            ViewStub backButtonStub = (ViewStub) findViewById(R.id.nav_back_stub);
+            mNavBackButton = (ImageButton) backButtonStub.inflate( );
+            mNavBackButton.setOnClickListener(new Button.OnClickListener() {
+                @Override
+                public void onClick(View view) {
+                    mActivity.onBackPressed();
+                }
+            });
+        }
     }
 
     public void showMenu() {