[java-runtime] simplify mono.MonoPackageManager.LoadApplication() (#9655)

We currently have code that loads `MonoRuntimeProvider.Bundled.java`
and parses Java code comments between:

	// Mono Runtime Initialization {{{
	android.content.pm.ApplicationInfo applicationInfo = context.getApplicationInfo ();
	String[] apks = null;
	String[] splitApks = applicationInfo.splitSourceDirs;
	if (splitApks != null && splitApks.length > 0) {
	    apks = new String[splitApks.length + 1];
	    apks [0] = applicationInfo.sourceDir;
	    System.arraycopy (splitApks, 0, apks, 1, splitApks.length);
	} else {
	    apks = new String[] { applicationInfo.sourceDir };
	}
	mono.MonoPackageManager.LoadApplication (context, applicationInfo, apks);
	// }}}

These lines are used for any `Instrumentation` type, such as:

https://github.com/dotnet/java-interop/blob/2c06b3c2a11833aea0e9b51aac2a72195bd64539/src/Java.Interop.Tools.JavaCallableWrappers/Java.Interop.Tools.JavaCallableWrappers.CallableWrapperMembers/CallableWrapperType.cs#L238-L241

To refactor and cleanup, we can:

  * Make `mono.MonoPackageManager.LoadApplication()` only take in a
    single `Context context` parameter.

  * Move the Java code that looks at `applicationInfo.splitSourceDirs`
    inside `mono.MonoPackageManager.LoadApplication()`.

  * Reduce the code in the `// Mono Runtime Initialization {{{` block
    to a single line.

  * Now we no longer need to load the
    `MonoRuntimeProvider.Bundled.java` file during a build, we can
    simply declare the one line of Java code as a C# string.

This will make refactoring `<GenerateJavaStubs/>` easier in future PRs.

Author: jonathanpeppers

src/Xamarin.Android.Build.Tasks/Resources/MonoRuntimeProvider.Bundled.java

@@ -18,19 +18,7 @@ public boolean onCreate ()
 	@Override
 	public void attachInfo (android.content.Context context, android.content.pm.ProviderInfo info)
 	{
-		// Mono Runtime Initialization {{{
-		android.content.pm.ApplicationInfo applicationInfo = context.getApplicationInfo ();
-		String[] apks = null;
-		String[] splitApks = applicationInfo.splitSourceDirs;
-		if (splitApks != null && splitApks.length > 0) {
-			apks = new String[splitApks.length + 1];
-			apks [0] = applicationInfo.sourceDir;
-			System.arraycopy (splitApks, 0, apks, 1, splitApks.length);
-		} else {
-			apks = new String[] { applicationInfo.sourceDir };
-		}
-		mono.MonoPackageManager.LoadApplication (context, applicationInfo, apks);
-		// }}}
+		mono.MonoPackageManager.LoadApplication (context);
 		super.attachInfo (context, info);
 	}
 

src/Xamarin.Android.Build.Tasks/Utilities/JCWGenerator.cs

@@ -99,7 +99,7 @@ bool ProcessTypes (bool generateCode, string androidSdkPlatform, MarshalMethodsC
 			throw new ArgumentException ("must not be null or empty", nameof (outputPath));
 		}
 
-		string monoInit = GetMonoInitSource (androidSdkPlatform);
+		string monoInit = "mono.MonoPackageManager.LoadApplication (context);";
 		bool hasExportReference = context.ResolvedAssemblies.Any (assembly => Path.GetFileName (assembly.ItemSpec) == "Mono.Android.Export.dll");
 		bool ok = true;
 
@@ -185,44 +185,6 @@ CallableWrapperType CreateGenerator (TypeDefinition type, MarshalMethodsClassifi
 		return CecilImporter.CreateType (type, context.TypeDefinitionCache, reader_options);
 	}
 
-	static string GetMonoInitSource (string androidSdkPlatform)
-	{
-		if (String.IsNullOrEmpty (androidSdkPlatform)) {
-			throw new ArgumentException ("must not be null or empty", nameof (androidSdkPlatform));
-		}
-
-		// Lookup the mono init section from MonoRuntimeProvider:
-		// Mono Runtime Initialization {{{
-		// }}}
-		var builder = new StringBuilder ();
-		var runtime = "Bundled";
-		var api = "";
-		if (int.TryParse (androidSdkPlatform, out int apiLevel) && apiLevel < 21) {
-			api = ".20";
-		}
-
-		var assembly = Assembly.GetExecutingAssembly ();
-		using var s = assembly.GetManifestResourceStream ($"MonoRuntimeProvider.{runtime}{api}.java");
-		using var reader = new StreamReader (s);
-		bool copy = false;
-		string? line;
-		while ((line = reader.ReadLine ()) != null) {
-			if (string.CompareOrdinal ("\t\t// Mono Runtime Initialization {{{", line) == 0) {
-				copy = true;
-			}
-
-			if (copy) {
-				builder.AppendLine (line);
-			}
-
-			if (string.CompareOrdinal ("\t\t// }}}", line) == 0) {
-				break;
-			}
-		}
-
-		return builder.ToString ();
-	}
-
 	public static void EnsureAllArchitecturesAreIdentical (TaskLoggingHelper logger, ConcurrentDictionary<AndroidTargetArch, NativeCodeGenState> javaStubStates)
 	{
 		if (javaStubStates.Count <= 1) {

src/java-runtime/java/mono/android/MonoPackageManager.java

@@ -26,9 +26,20 @@ public class MonoPackageManager {
 
 	static android.content.Context Context;
 
-	public static void LoadApplication (Context context, ApplicationInfo runtimePackage, String[] apks)
+	public static void LoadApplication (Context context)
 	{
 		synchronized (lock) {
+			android.content.pm.ApplicationInfo runtimePackage = context.getApplicationInfo ();
+			String[] apks = null;
+			String[] splitApks = runtimePackage.splitSourceDirs;
+			if (splitApks != null && splitApks.length > 0) {
+				apks = new String[splitApks.length + 1];
+				apks [0] = runtimePackage.sourceDir;
+				System.arraycopy (splitApks, 0, apks, 1, splitApks.length);
+			} else {
+				apks = new String[] { runtimePackage.sourceDir };
+			}
+
 			if (context instanceof android.app.Application) {
 				Context = context;
 			}