P.S.Will not be released until NACL is supported as part of Chrome extension development
P.S.A .patch file needs to be created for the ffmpeg-0.5 from NACLPort. Bug: Trailing commas in some of the lib file
Setup Steps

##Install NACL

• Download NACL SDK here
• unzip nacl_sdk.zip and run ./nacl_sdk list to check available versions and ./nacl_sdk update to download
• set environment variable NACL_SDK_ROOT=/where/nacl_sdk/is

##Install NACLPort

• Download NACLPort and follow the instruction here

##Install Dependencies through NACLPort

* Export `NACL_PORTS` env variable to point to where you installed nacl ports.
* Run `./deps.sh`.         

##Compile and Run

• Run make. .nexe and _32.o/_64.o files should be generated.

Development Documentation

###mediaRequestProbe.js

• This is the background script.
• chrome.webRequest.onBeforeRequest gets web requests. mediaReqeustsMap holds request metadata.
• Message passing, icon animation, triggering notifications.

###popup.html / popup.js

• Display available download entries if available.
• Pass message back to the background script triggering notification windows for download options

###notification.html / notification.js

• Display download options according the original file format.e.g.if the file is .mp4, mp3 and original show up as download options
• Passing download meta data(URL, vidID, current format and the conversion format,etc) to the NACL transcoder.

###listener.js

• Communication between NACL and client-side js.

###transcoder.cc / transcoder.h

• transcoding(In Progresss) options: MP4->MP3, FLV->MP4/MP3.
• TODO: implement using ffmpeg/libav.
• libav libs need to be patched due to the trailing comma bug.(will see the errors when first time compile, after porting libav from the NACLPort)