Call hook in java_sdk_library after droidstubs generation

Currently, droidstubs module create java_api_contribution module, but
when a java_sdk_library module dynamically creates a droidstubs module,
java_api_contribution is not created as the hook inside droidstubs get
lost. Therefore, call hook inside sdk_library after creating the
droidstubs module.

Test: m
Change-Id: I68bf1d796f6f9a6f81011ae35e4991b6ed1421ea
diff --git a/android/defaults.go b/android/defaults.go
index 7906e94..925eafc 100644
--- a/android/defaults.go
+++ b/android/defaults.go
@@ -55,7 +55,7 @@
 	d.hook = hook
 }
 
-func (d *DefaultableModuleBase) callHookIfAvailable(ctx DefaultableHookContext) {
+func (d *DefaultableModuleBase) CallHookIfAvailable(ctx DefaultableHookContext) {
 	if d.hook != nil {
 		d.hook(ctx)
 	}
@@ -82,7 +82,7 @@
 	SetDefaultableHook(hook DefaultableHook)
 
 	// Call the hook if specified.
-	callHookIfAvailable(context DefaultableHookContext)
+	CallHookIfAvailable(context DefaultableHookContext)
 }
 
 type DefaultableModule interface {
@@ -630,6 +630,6 @@
 			defaultable.applyDefaults(ctx, defaultsList)
 		}
 
-		defaultable.callHookIfAvailable(ctx)
+		defaultable.CallHookIfAvailable(ctx)
 	}
 }