Use one mutator for all bp2build conversion.

Each conversion required defining a separate mutator, which will each
operate on _all_ modules and requires each to repeat checks whether the
mutator should operator. Instead, we introduce a single mutator and
modules can define a ConvertWithBp2build to implement bp2build
conversion for that module.

Test: bp2build.sh
Bug: 183079158
Change-Id: I99d4b51f441c2903879092c5b56313d606d4338d
diff --git a/cc/binary.go b/cc/binary.go
index e839122..50175d9 100644
--- a/cc/binary.go
+++ b/cc/binary.go
@@ -69,13 +69,14 @@
 
 // cc_binary produces a binary that is runnable on a device.
 func BinaryFactory() android.Module {
-	module, _ := NewBinary(android.HostAndDeviceSupported)
+	module, _ := newBinary(android.HostAndDeviceSupported, true)
 	return module.Init()
 }
 
 // cc_binary_host produces a binary that is runnable on a host.
 func BinaryHostFactory() android.Module {
-	module, _ := NewBinary(android.HostSupported)
+	module, _ := newBinary(android.HostSupported, true)
+	module.bazelable = true
 	return module.Init()
 }
 
@@ -193,6 +194,10 @@
 // Individual module implementations which comprise a C++ binary should call this function,
 // set some fields on the result, and then call the Init function.
 func NewBinary(hod android.HostOrDeviceSupported) (*Module, *binaryDecorator) {
+	return newBinary(hod, true)
+}
+
+func newBinary(hod android.HostOrDeviceSupported, bazelable bool) (*Module, *binaryDecorator) {
 	module := newModule(hod, android.MultilibFirst)
 	binary := &binaryDecorator{
 		baseLinker:    NewBaseLinker(module.sanitize),
@@ -201,6 +206,7 @@
 	module.compiler = NewBaseCompiler()
 	module.linker = binary
 	module.installer = binary
+	module.bazelable = bazelable
 
 	// Allow module to be added as member of an sdk/module_exports.
 	module.sdkMemberTypes = []android.SdkMemberType{
@@ -551,33 +557,7 @@
 	})
 }
 
-func init() {
-	android.RegisterBp2BuildMutator("cc_binary", BinaryBp2build)
-	android.RegisterBp2BuildMutator("cc_binary_host", BinaryHostBp2build)
-}
-
-func BinaryBp2build(ctx android.TopDownMutatorContext) {
-	binaryBp2build(ctx, "cc_binary")
-}
-
-func BinaryHostBp2build(ctx android.TopDownMutatorContext) {
-	binaryBp2build(ctx, "cc_binary_host")
-}
-
-func binaryBp2build(ctx android.TopDownMutatorContext, typ string) {
-	m, ok := ctx.Module().(*Module)
-	if !ok {
-		// Not a cc module
-		return
-	}
-	if !m.ConvertWithBp2build(ctx) {
-		return
-	}
-
-	if ctx.ModuleType() != typ {
-		return
-	}
-
+func binaryBp2build(ctx android.TopDownMutatorContext, m *Module, typ string) {
 	var compatibleWith bazel.StringListAttribute
 	if typ == "cc_binary_host" {
 		//incompatible with android OS