Bug 1098459 - Remove dead area on the right of "new tab" button (r=mcomella)

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

@@ -12,6 +12,8 @@
         android:layout_weight="1"
         android:paddingTop="4dp"/>
 
+    <!-- The right margin creates a "dead area" on the right side of the button
+         which we compensate for with a touch delegate. See TabStrip -->
     <ImageButton
         android:id="@+id/add_tab"
         style="@style/UrlBar.ImageButton"

mobile/android/base/tabs/TabStrip.java

@@ -6,9 +6,12 @@
 package org.mozilla.gecko.tabs;
 
 import android.content.Context;
+import android.graphics.Rect;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
+import android.view.TouchDelegate;
 import android.view.View;
+import android.view.ViewTreeObserver;
 import android.widget.ImageButton;
 
 import org.mozilla.gecko.R;
@@ -51,6 +54,25 @@ public class TabStrip extends ThemedLinearLayout {
             }
         });
 
+        getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
+                @Override
+                public boolean onPreDraw() {
+                    getViewTreeObserver().removeOnPreDrawListener(this);
+
+                    final Rect r = new Rect();
+                    r.left = addTabButton.getRight();
+                    r.right = getWidth();
+                    r.top = 0;
+                    r.bottom = getHeight();
+
+                    // Redirect touch events between the 'new tab' button and the edge
+                    // of the screen to the 'new tab' button.
+                    setTouchDelegate(new TouchDelegate(r, addTabButton));
+
+                    return true;
+                }
+            });
+
         tabsListener = new TabsListener();
     }