I am using PL2303 USB to TTL adapter to program ESP8266, but I do not want to unplug it from system and plug it into PL2303 all the time. That's why I want to program it in system, with my AVR (the AVR is already connected to ESP8266 in the device that I intended to build).
What I want to achieve is that I just restart ESP8266 in flash mode (by hand. It is not a big deal, I can do it myself) and program it using AVR.
I could not ask a clearer question, because I couldn't think of any close solution. Please tolerate my confusion.
NOTE: Uploading a code to AVR which makes AVR act like USB to TTL adapter can be an option for me. That way, I can upload the code I wrote for ESP8266 through AVR.
NOTE 2: I am seeking for a help that eliminates the requirement of PL2303 and use directly AVR to program ESP.