title: Issue with automatically injecting activities with Dagger 2
body: <p>I am still pretty new to Daggers dependency injection. I am working on a new application utilizing Dagger 2 and Kotlin. I started with a basic starter app meant for building on. Within App.kt every activity is being injected automatically, which up until now is pretty cool. However I am running into an issue now with implementing Facebook and Google social logins.</p>
  
  <p>When the app tries to launch Facebook or Googles sign in activities I get the error:</p>
  
  <p><code>"No injector factory bound for Class&lt;external.activities.classNameHere&gt;"</code></p>
  
  <p>I cannot @Provides those external classes since they do not implement the @Module annotation.</p>
  
  <p>My temporary solution is to check the activity being injected before the automatic injection, and skip those external classes. This seems a little odd though, I am wondering if there is a better solution to this or if I am missing something. I can see this if statement getting pretty long over time.</p>
  
  <pre><code> registerActivityLifecycleCallbacks(object : ActivityLifecycleCallbacks() {
          override fun onActivityCreated(p0: Activity?, p1: Bundle?) {
              p0?.let {
                  if (p0 is FacebookActivity || p0 is CustomTabMainActivity || p0 is CustomTabActivity ) {
                      Log.d("KSULog", "App.kt is not injecting activity " + p0.toString())
                  }
                  else {
                      AndroidInjection.inject(p0)
                  }
  
              }
          }
      })
  }
  </code></pre>
  
  <p>Thanks for taking a look.</p>