Clean up listeners and tag on ButtonRenderer during disposal (#360)

Clean up OnFocusChangeListener on ViewRenderer during disposal
Prevent memory leak of PageContainer/FragmentContainer when animating fragment transitions
Call Destroy() on Map during disposal

Rebasing

2 files changed, 76 insertions, 0 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla39489.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla39489.cs
new file mode 100644
index 00000000..266b0fa6
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla39489.cs
@@ -0,0 +1,75 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System.Threading;
+using System;
+using System.Threading.Tasks;
+using Xamarin.Forms.Maps;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 39489, "Memory leak when using NavigationPage with Maps", PlatformAffected.Android)]
+	public class Bugzilla39489 : TestNavigationPage
+	{
+		protected override void Init()
+		{
+			PushAsync(new Bz39489Content());
+		}
+
+		#if UITEST
+		[Test]
+		public async void Bugzilla39458Test()
+		{
+			// Original bug report (https://bugzilla.xamarin.com/show_bug.cgi?id=39489) had a crash (OOM) after 25-30
+			// page loads. Obviously it's going to depend heavily on the device and amount of available memory, but
+			// if this starts failing before 50 we'll know we've sprung another serious leak
+			int iterations = 50;
+
+			for (int n = 0; n < iterations; n++)
+			{
+				RunningApp.WaitForElement(q => q.Marked("New Page"));
+				RunningApp.Tap(q => q.Marked("New Page"));
+				RunningApp.WaitForElement(q => q.Marked("New Page"));
+				await Task.Delay(1000);
+				RunningApp.Back();
+			}
+		}
+		#endif
+	}
+
+	[Preserve(AllMembers = true)]
+	public class Bz39489Content : ContentPage
+	{
+		public Bz39489Content()
+		{
+			var button = new Button { Text = "New Page" };
+
+			var gcbutton = new Button { Text = "GC" };
+
+			var map = new Map();
+
+			button.Clicked += Button_Clicked;
+			gcbutton.Clicked += GCbutton_Clicked;
+
+			Content = new StackLayout { Children = { button, gcbutton, map } };
+		}
+
+		void GCbutton_Clicked(object sender, EventArgs e)
+		{
+			System.Diagnostics.Debug.WriteLine(">>>>>>>> Running Garbage Collection");
+			GC.Collect();
+			GC.WaitForPendingFinalizers();
+			System.Diagnostics.Debug.WriteLine($">>>>>>>> GC.GetTotalMemory = {GC.GetTotalMemory(true):n0}");
+		}
+
+		void Button_Clicked(object sender, EventArgs e)
+		{
+			Navigation.PushAsync(new Bz39489Content());
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index 364b3c44..7a47c10f 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -437,6 +437,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue55555.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla41029.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla39908.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla39489.cs" />
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Bugzilla22229.xaml">