Added PoppedToRootEventArgs to track popped pages when calling PopToRoot

Xamarin.Forms.Core.UnitTests/NavigationUnitTest.cs

@@ -187,6 +187,31 @@ public async Task TestPopToRoot ()
 			Assert.AreEqual (root, nav.CurrentPage);
 		}
 
+		[Test]
+		public async Task TestPopToRootEventArgs ()
+		{
+			var nav = new NavigationPage ();
+
+			List<Page> poppedChildren = null;
+            nav.PoppedToRoot += (sender, args) => poppedChildren = (args as PoppedToRootEventArgs).PoppedPages.ToList();
+
+			var root = new ContentPage {Content = new View ()};
+			var child1 = new ContentPage {Content = new View ()};
+			var child2 = new ContentPage {Content = new View ()};
+
+			await nav.PushAsync (root);
+			await nav.PushAsync (child1);
+			await nav.PushAsync (child2);
+
+			await nav.PopToRootAsync ();
+
+			Assert.IsNotNull (poppedChildren);
+			Assert.AreEqual (2, poppedChildren.Count);
+			Assert.Contains (child1, poppedChildren);
+			Assert.Contains (child2, poppedChildren);
+			Assert.AreEqual (root, nav.CurrentPage);
+		}
+
 		[Test]
 		public async Task TestStackCopy ()
 		{

Xamarin.Forms.Core/NavigationPage.cs

@@ -319,7 +319,9 @@ async Task PopToRootAsyncInner(bool animated)
 
 			var root = (Page)PageController.InternalChildren.First();
 
-			PageController.InternalChildren.ToArray().Where(c => c != root).ForEach(c => PageController.InternalChildren.Remove(c));
+            var childrenToRemove = PageController.InternalChildren.ToArray().Where(c => c != root);
+            foreach (var child in childrenToRemove)
+                PageController.InternalChildren.Remove(child);
 
 			CurrentPage = root;
 
@@ -335,7 +337,7 @@ async Task PopToRootAsyncInner(bool animated)
 			}
 
 			if (PoppedToRoot != null)
-				PoppedToRoot(this, new NavigationEventArgs(root));
+                PoppedToRoot(this, new PoppedToRootEventArgs(root, childrenToRemove.OfType<Page>().ToList()));
 		}
 
 		async Task PushAsyncInner(Page page, bool animated)

Xamarin.Forms.Core/PoppedToRootEventArgs.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+
+namespace Xamarin.Forms
+{
+	public class PoppedToRootEventArgs : NavigationEventArgs
+	{
+		public PoppedToRootEventArgs(Page page, IEnumerable<Page> poppedPages) : base(page)
+		{
+            if (poppedPages == null)
+                throw new ArgumentNullException(nameof(poppedPages));
+
+            PoppedPages = poppedPages;
+		}
+
+        public IEnumerable<Page> PoppedPages { get; private set; }
+	}
+}

Xamarin.Forms.Core/Xamarin.Forms.Core.csproj

@@ -415,6 +415,7 @@
     <Compile Include="IApplicationController.cs" />
     <Compile Include="IAppIndexingProvider.cs" />
     <Compile Include="ListStringTypeConverter.cs" />
+    <Compile Include="PoppedToRootEventArgs.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <ItemGroup>

docs/Xamarin.Forms.Core/Xamarin.Forms/NavigationPage.xml

@@ -477,7 +477,9 @@
       </ReturnValue>
       <Docs>
         <summary>Event that is raised when the last nonroot element is popped from this <see cref="T:Xamarin.Forms.NavigationPage" /> element.</summary>
-        <remarks>To be added.</remarks>
+        <remarks>The <see cref="T:Xamarin.Forms.NavigationEventArgs" /> can be cast to <see cref="T:Xamarin.Forms.PoppedToRootEventArgs" /> for 
+        access to additional properties. For example, the list of popped pages.
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="PopToRootAsync">

docs/Xamarin.Forms.Core/Xamarin.Forms/PoppedToRootEventArgs.xml

@@ -0,0 +1,60 @@
+<Type Name="PoppedToRootEventArgs" FullName="Xamarin.Forms.PoppedToRootEventArgs">
+  <TypeSignature Language="C#" Value="public class PoppedToRootEventArgs : Xamarin.Forms.NavigationEventArgs" />
+  <TypeSignature Language="ILAsm" Value=".class public auto ansi beforefieldinit PoppedToRootEventArgs extends Xamarin.Forms.NavigationEventArgs" />
+  <AssemblyInfo>
+    <AssemblyName>Xamarin.Forms.Core</AssemblyName>
+    <AssemblyVersion>2.0.0.0</AssemblyVersion>
+  </AssemblyInfo>
+  <Base>
+    <BaseTypeName>Xamarin.Forms.NavigationEventArgs</BaseTypeName>
+  </Base>
+  <Interfaces />
+  <Docs>
+    <summary>EventArgs for the NavigationPage's PoppedToRoot navigation event.</summary>
+    <remarks>
+        The <see cref="E:Xamarin.Forms.NavigationPage.PoppedToRoot" /> passes <see cref="T:Xamarin.Forms.NavigationEventArgs" /> as the
+        event argument. This class can be cast to <see cref="T:Xamarin.Forms.PoppedToRootEventArgs" /> to allow for access to the
+        PoppedPages collection that exposes the pages that was popped.
+    </remarks>
+    <altmember cref="E:Xamarin.Forms.NavigationPage.PoppedToRoot" />
+  </Docs>
+  <Members>
+    <Member MemberName=".ctor">
+      <MemberSignature Language="C#" Value="public PoppedToRootEventArgs (Xamarin.Forms.Page page);" />
+      <MemberSignature Language="ILAsm" Value=".method public hidebysig specialname rtspecialname instance void .ctor(class Xamarin.Forms.Page page) cil managed" />
+      <MemberType>Constructor</MemberType>
+      <AssemblyInfo>
+        <AssemblyVersion>2.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <Parameters>
+        <Parameter Name="page" Type="Xamarin.Forms.Page" />
+      </Parameters>
+      <Docs>
+        <param name="page">The page that is the new root page.</param>
+        <summary></summary>
+        <remarks></remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="PoppedPages">
+      <MemberSignature Language="C#" Value="public System.Collections.Generic.IEnumerable&lt;Xamarin.Forms.Page&gt; PoppedPages { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance class System.Collections.Generic.IEnumerable`1&lt;class Xamarin.Forms.Page&gt; PoppedPages" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo>
+        <AssemblyVersion>2.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.Collections.Generic.IEnumerable&lt;Xamarin.Forms.Page&gt;</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>Gets a collection of pages that was removed from the navigation stack.</summary>
+        <value></value>
+        <remarks>
+          <para>For <see cref="E:Xamarin.Forms.NavigationPage.PoppedToRoot" /> this represents the pages
+          that were popped. The order of the pages represents the order of the stack that was popped. The first page in the
+          collection is the page that was closest to the root page.
+          </para>
+        </remarks>
+      </Docs>
+    </Member>
+  </Members>
+</Type>