As the project grows, the src/ directory has become a bit mess, we should separate source files into different sub directories and follow what chrome did.
Part of refactor #43.
Put renderer code to renderer/ .
Put url_request_context_getter under net/ .
Move nw.gypi into this project.
Part of refactor #43 .
Move all dialogs stuff into browser/ .
Move shell_switches into common/ .
Remove unused shell_messages.
Refactor should be done now.