Remove internal deapexer module

The build ations will be created by the top-level apex.

Details
1. In GenerateAndroidBuildActions, do a graph walk to determine if the
   apex has exported deps.
2. If there are exported deps, call the newly introduced `deapex`
   function. This registers the build rules and returns a DeapexerInfo
object. This was previously provided by the internal deapexer
dependency.
3. Update `dexpreoptSystemServerJars and `provideApexExportsInfo` to use
   the DeapexerInfo object from (2).

A lot of unit tests that relied on the legacy mechanism of deapexing
have been updated.

Test: go test ./apex
Test: lunch cf_x86_64_phone-next-userdebug (uses mainline prebuilts)
Test: verified no diff in file_list.txt
Bug: 368337090
Change-Id: I0edb681beccac4d2a9ceb73f9a506c081a8a96e0
diff --git a/apex/deapexer.go b/apex/deapexer.go
index a673108..3b8233d 100644
--- a/apex/deapexer.go
+++ b/apex/deapexer.go
@@ -15,37 +15,9 @@
 package apex
 
 import (
-	"strings"
-
 	"android/soong/android"
 )
 
-// Contains 'deapexer' a private module type used by 'prebuilt_apex' to make dex files contained
-// within a .apex file referenced by `prebuilt_apex` available for use by their associated
-// `java_import` modules.
-//
-// An 'apex' module references `java_library` modules from which .dex files are obtained that are
-// stored in the resulting `.apex` file. The resulting `.apex` file is then made available as a
-// prebuilt by referencing it from a `prebuilt_apex`. For each such `java_library` that is used by
-// modules outside the `.apex` file a `java_import` prebuilt is made available referencing a jar
-// that contains the Java classes.
-//
-// When building a Java module type, e.g. `java_module` or `android_app` against such prebuilts the
-// `java_import` provides the classes jar  (jar containing `.class` files) against which the
-// module's `.java` files are compiled. That classes jar usually contains only stub classes. The
-// resulting classes jar is converted into a dex jar (jar containing `.dex` files). Then if
-// necessary the dex jar is further processed by `dexpreopt` to produce an optimized form of the
-// library specific to the current Android version. This process requires access to implementation
-// dex jars for each `java_import`. The `java_import` will obtain the implementation dex jar from
-// the `.apex` file in the associated `prebuilt_apex`.
-//
-// This is intentionally not registered by name as it is not intended to be used from within an
-// `Android.bp` file.
-
-// DeapexerProperties specifies the properties supported by the deapexer module.
-//
-// As these are never intended to be supplied in a .bp file they use a different naming convention
-// to make it clear that they are different.
 type DeapexerProperties struct {
 	// List of common modules that may need access to files exported by this module.
 	//
@@ -72,46 +44,9 @@
 	Selected_apex *string `android:"path" blueprint:"mutated"`
 }
 
-type Deapexer struct {
-	android.ModuleBase
-
-	properties             DeapexerProperties
-	selectedApexProperties SelectedApexProperties
-
-	inputApex android.Path
-}
-
-// Returns the name of the deapexer module corresponding to an APEX module with the given name.
-func deapexerModuleName(apexModuleName string) string {
-	return apexModuleName + ".deapexer"
-}
-
-// Returns the name of the APEX module corresponding to an deapexer module with
-// the given name. This reverses deapexerModuleName.
-func apexModuleName(deapexerModuleName string) string {
-	return strings.TrimSuffix(deapexerModuleName, ".deapexer")
-}
-
-func privateDeapexerFactory() android.Module {
-	module := &Deapexer{}
-	module.AddProperties(&module.properties, &module.selectedApexProperties)
-	android.InitAndroidMultiTargetsArchModule(module, android.DeviceSupported, android.MultilibCommon)
-	return module
-}
-
-func (p *Deapexer) DepsMutator(ctx android.BottomUpMutatorContext) {
-	// Add dependencies from the java modules to which this exports files from the `.apex` file onto
-	// this module so that they can access the `DeapexerInfo` object that this provides.
-	// TODO: b/308174306 - Once all the mainline modules have been flagged, drop this dependency edge
-	for _, lib := range p.properties.CommonModules {
-		dep := prebuiltApexExportedModuleName(ctx, lib)
-		ctx.AddReverseDependency(ctx.Module(), android.DeapexerTag, dep)
-	}
-}
-
-func (p *Deapexer) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	p.inputApex = android.OptionalPathForModuleSrc(ctx, p.selectedApexProperties.Selected_apex).Path()
-
+// deapex creates the build rules to deapex a prebuilt .apex file
+// it returns a pointer to a DeapexerInfo object
+func deapex(ctx android.ModuleContext, apexFile android.Path, deapexerProps DeapexerProperties) *android.DeapexerInfo {
 	// Create and remember the directory into which the .apex file's contents will be unpacked.
 	deapexerOutput := android.PathForModuleOut(ctx, "deapexer")
 
@@ -119,7 +54,7 @@
 
 	// Create mappings from apex relative path to the extracted file's path.
 	exportedPaths := make(android.Paths, 0, len(exports))
-	for _, path := range p.properties.ExportedFiles {
+	for _, path := range deapexerProps.ExportedFiles {
 		// Populate the exports that this makes available.
 		extractedPath := deapexerOutput.Join(ctx, path)
 		exports[path] = extractedPath
@@ -131,9 +66,8 @@
 	// apex relative path to extracted file path available for other modules.
 	if len(exports) > 0 {
 		// Make the information available for other modules.
-		di := android.NewDeapexerInfo(apexModuleName(ctx.ModuleName()), exports, p.properties.CommonModules)
-		di.AddDexpreoptProfileGuidedExportedModuleNames(p.properties.DexpreoptProfileGuidedModules...)
-		android.SetProvider(ctx, android.DeapexerProvider, di)
+		di := android.NewDeapexerInfo(ctx.ModuleName(), exports, deapexerProps.CommonModules)
+		di.AddDexpreoptProfileGuidedExportedModuleNames(deapexerProps.DexpreoptProfileGuidedModules...)
 
 		// Create a sorted list of the files that this exports.
 		exportedPaths = android.SortedUniquePaths(exportedPaths)
@@ -147,11 +81,13 @@
 			BuiltTool("deapexer").
 			BuiltTool("debugfs").
 			BuiltTool("fsck.erofs").
-			Input(p.inputApex).
+			Input(apexFile).
 			Text(deapexerOutput.String())
 		for _, p := range exportedPaths {
 			command.Output(p.(android.WritablePath))
 		}
-		builder.Build("deapexer", "deapex "+apexModuleName(ctx.ModuleName()))
+		builder.Build("deapexer", "deapex "+ctx.ModuleName())
+		return &di
 	}
+	return nil
 }