docs: Using Widevine CDM Plugin

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 * [Using Selenium and WebDriver](tutorial/using-selenium-and-webdriver.md)
 * [DevTools Extension](tutorial/devtools-extension.md)
 * [Using Pepper Flash Plugin](tutorial/using-pepper-flash-plugin.md)
+* [Using Widevine CDM Plugin](tutorial/using-widevine-cdm-plugin.md)
 
 ## Tutorials
 

diff --git a/docs/tutorial/using-widevine-cdm-plugin.md b/docs/tutorial/using-widevine-cdm-plugin.md
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+# Using Widevine CDM Plugin
+
+In Electron you can use the Widevine CDM plugin shipped with Chrome browser.
+
+## Getting the plugin
+
+Electron doesn't ship with the Widevine CDM plugin for license reasons, to get
+it, you need to install the official Chrome browser first, which should match
+the architecture and Chrome version of the Electron build you use.
+
+### Windows & OS X
+
+Open `chrome://components/` in Chrome browser, find `WidevineCdm` and make
+sure it is up to date, then you can find all the plugin binaries from the
+`APP_DATA/Google/Chrome/WidevineCDM/VERSION/_platform_specific/PLATFORM_ARCH/`
+directory.
+
+`APP_DATA` is system's location for storing app data, on Windows it is
+`%LOCALAPPDATA%`, on OS X it is `~/Library/Application Support`. `VERSION` is
+Widevine CDM plugin's version string, like `1.4.8.866`. `PLATFORM` is `mac` or
+`win`. `ARCH` is `x86` or `x64`.
+
+On Windows the required binaries are `widevinecdm.dll` and
+`widevinecdmadapter.dll`, on OS X they are `libwidevinecdm.dylib` and
+`widevinecdmadapter.plugin`. You can copy them to anywhere you like, but they
+have to be put together.
+
+### Linux
+
+On Linux the plugin binaries are shipped together with Chrome browser, you can
+find them under `/opt/google/chrome`, the filenames are `libwidevinecdm.so` and
+`libwidevinecdmadapter.so`.
+
+## Using the plugin
+
+After getting the plugin files, you should pass the `widevinecdmadapter`'s path
+to Electron with `--widevine-cdm-path` command line switch, and the plugin's
+version with `--widevine-cdm-version` switch.
+
+__Note:__ Though only the `widevinecdmadapter` binary is passed to Electron, the
+`widevinecdm` binary has to be put aside it.
+
+The command line switches have to be passed before the `ready` event of `app`
+module gets emitted, and the page that uses this plugin must have plugin
+enabled.
+
+Example code:
+
+```javascript
+// You have to pass the filename of `widevinecdmadapter` here, it is
+// * `widevinecdmadapter.plugin` on OS X,
+// * `libwidevinecdmadapter.so` on Linux,
+// * `widevinecdmadapter.dll` on Windows.
+app.commandLine.appendSwitch('widevine-cdm-path', '/path/to/widevinecdmadapter.plugin');
+// The version of plugin can be got from `chrome://plugins` page in Chrome.
+app.commandLine.appendSwitch('widevine-cdm-version', '1.4.8.866');
+
+var mainWindow = null;
+app.on('ready', function() {
+  mainWindow = new BrowserWindow({
+    webPreferences: {
+      // The `plugins` have to be enabled.
+      plugins: true
+    }
+  })
+});
+```
+
+## Verifying the plugin
+
+To verify whether the plugin works, you can use following ways:
+
+* Open devtools and check whether `navigator.plugins` includes the Widevine
+CDM plugin.
+* Open https://shaka-player-demo.appspot.com/ and load a manifest that uses
+`Widevine`.
+* Open http://www.dash-player.com/demo/drm-test-area/, check whether the page
+says `bitdash uses Widevine in your browser`, then play the video.