How to fix "adb devices" can't find Android device on Windows

Problem
Google Nexus 7 
Windows 7
Installed the latest Android sdk
"adb devices" couldn't find Android device when it was plugged in and USB debugging enabled

How to solve it

1. Adding the new device reference in android_winusb.inf
in C:\Android\sdk\extras\google\usb_driver

Right click your Android device in your computer's "Device Manager", select "properties", Details Tab and from the dropdown Property list select "Hardware Ids". Copy the 2 values in your clipboard.

Edit the android_winusb.inf file included with the Google USB Drivers (the location on my machine is "C:\Android\sdk\extras\google\usb_driver" and add these lines using the 2 values in your clipboard:

; your device model
%SingleAdbInterface%        = USB_Install, Clipboard first value
%CompositeAdbInterface%     = USB_Install, Clipboard second value

after the last lines of the [Google.NTx86] section.

2. Updated the drivers in your computer's Device Manager. (You need admin right to do this)

Device Manager -> Portable devices, right click the Android device in Device Manager -> Change settings (need admin right), uninstall the Android usb driver completely

unplug your Android device, re-plug back in,
update the driver, and manually point it to the google usb driver in "C:\Android\sdk\extras\google\usb_driver" (just select this directory)

3. In Command window, run 'adb devices'.
At this point adb should recognize the device (as an unauthorized device)

4. You will then see a dialog on your Android device, asking whether to accept an RSA key that allows debugging through this computer. Click Ok

(if you don't see this dialog on your phone, unplug your phone from the computer and plug it back in.)

run 'adb devices' again
This time the device will be authorized.