Restructure AbstractRequestHandler so that it can be unit tested.
user
```ruby
require 'support/config'
require 'support/test_helper'
require 'passenger/abstract_request_handler'

include Passenger

describe AbstractRequestHandler do
	before :each do
		@owner_pipe = IO.pipe
		@request_handler = AbstractRequestHandler.new(@owner_pipe[1])
		def @request_handler.process_request(*args)
			# Do nothing.
		end
	end
	
	after :each do
		@request_handler.cleanup
		@owner_pipe[0].close rescue nil
	end
	
	it "exits if the owner pipe is closed" do
		@request_handler.start_main_loop_thread
		@owner_pipe[0].close
		begin
			Timeout.timeout(5) do
				while @request_handler.main_loop_running?
					sleep 0.01
				end
			end
		rescue Timeout::Error
			violated
		end
	end
	
	it "ignores new connections that don't send any data" do
		def @request_handler.accept_connection
			return nil
		end
		@request_handler.start_main_loop_thread
		while @request_handler.iterations == 0
			sleep 0.01
		end
		@request_handler.processed_requests.should == 0
	end
end
```
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