No issue: add tips for reading Android source code.

Author: mcomella

android/android_guide.md

@@ -32,5 +32,13 @@ If you like staying up-to-date on the latest Android topics, members of our team
 Comfortable with the basics? Here are a few of our favorite resources to get started on intermediate topics.
 - [Android style tips](http://blog.danlew.net/2014/11/19/styles-on-android/) (circa 2014)
 
+### Navigating the Android source code
+Oftentimes, it's easier to solve a problem when you understand how your code is interacting with the Android framework: you can do this by reading the Android source code! You can do plain-text searches on the Android source code at http://androidxref.com/ (choosing the latest API level and searching in the "frameworks" is usually sufficient).
+
+You can also navigate the Android source code in Android Studio, after downloading the sources:
+- Click a framework method and use "go to definition"
+- Step into framework methods via the debugger
+- Set breakpoints in framework files to stop whenever the framework calls that method
+
 [udacity course]: https://www.udacity.com/course/new-android-fundamentals--ud851
 [devdocs]: https://developer.android.com/docs/