Just to confirm that DEPS file can be used for Java to help isolate them and clarify dependency, as we have a prescan pass that reads all the classes and builds a mapping of class name -> filepath. In java_checker.CheckFile() each import statement is converted to a real file path and checked against the rules in the DEPS files.

buildtools/checkdeps/java_checker.py 

A couple of observations:

1) With the include_rules in https://code.google.com/p/chromium/codesearch#chromium/src/chrome/android/java/DEPS taking effect, java classes' in chrome/ have well-enforced dependency on content/public/android/java, numerous components/, and sync/android/java/src/org/chromium/sync. The first 2 look okay, while sync/ looks a bit misplaced. I think it better be somewhere under chrome/. There may be a history related to this, which I'm not aware of.

2) I see  content/public java classes are grouped into two - content/public/android/java/src/org/chromium/{content_public, content}. If content_public is there to define the API for other apps like chrome/ to link content module to, I think the clearer distinction is necessary. Only the former should be referenced by chrome/ as API, leaving the latter as inaccessible implementation detail. That would be more aligned with c++ header/abstract class files in content/public/ vs. internal impl classes under other directories in content/.