How to calculate the number of bytes read in the active window Chrome browser?

[zxc3]

How to calculate the number of bytes read in the active window Chrome browser?
This program counts the number of bytes on the Yahoo site after pressing the F8 key.
But I need to be considered in the already open, the active window Chrome browser.

 

#include <MsgBoxConstants.au3>

HotKeySet("{F10}", "Terminate")
HotKeySet("{F8}", "Example")

;;;; Body of program would go here ;;;;

While 1
    Sleep(10000000)
WEnd
;;;;;;;;

Func Terminate()
    Exit 0
EndFunc

Func Example()
    ; Read the file without downloading to a folder. The option of 'get the file from the local cache' has been selected.
    Local $dData = InetRead("https://www.yahoo.com/")

    ; The number of bytes read is returned using the @extended macro.
    Local $iBytesRead = @extended

    ; Display the results.
    MsgBox($MB_SYSTEMMODAL, "", "The number of bytes read: " & $iBytesRead & @CRLF & @CRLF ) ;
EndFunc   ;==>Example