[NOT FOR REVIEW] extensions-wm: Add experimental extension API for window management.

chrome/common/extensions/docs/samples.json

 {
   "api": {
     "chrome.alarms.clear": "alarms.html#method-clear",
     "chrome.alarms.clearAll": "alarms.html#method-clearAll",
     "chrome.alarms.create": "alarms.html#method-create",
     "chrome.alarms.get": "alarms.html#method-get",
     "chrome.alarms.getAll": "alarms.html#method-getAll",
     "chrome.alarms.onAlarm": "alarms.html#event-onAlarm",
     "chrome.app.runtime.onLaunched": "app.runtime.html#event-onLaunched",
     "chrome.app.window.create": "app.window.html#method-create",
@@ skipping 167 matching lines @@
     "chrome.experimental.record.captureURLs": "experimental.record.html#method-captureURLs",
     "chrome.experimental.record.replayURLs": "experimental.record.html#method-replayURLs",
     "chrome.experimental.speechInput.isRecording": "experimental.speechInput.html#method-isRecording",
     "chrome.experimental.speechInput.onError": "experimental.speechInput.html#event-onError",
     "chrome.experimental.speechInput.onResult": "experimental.speechInput.html#event-onResult",
     "chrome.experimental.speechInput.onSoundEnd": "experimental.speechInput.html#event-onSoundEnd",
     "chrome.experimental.speechInput.onSoundStart": "experimental.speechInput.html#event-onSoundStart",
     "chrome.experimental.speechInput.start": "experimental.speechInput.html#method-start",
     "chrome.experimental.speechInput.stop": "experimental.speechInput.html#method-stop",
     "chrome.experimental.systemInfo.cpu.get": "experimental.systemInfo.cpu.html#method-get",
+    "chrome.experimental.systemInfo.storage.get": "experimental.systemInfo.storage.html#method-get",
     "chrome.experimental.usb.bulkTransfer": "experimental.usb.html#method-bulkTransfer",
     "chrome.experimental.usb.closeDevice": "experimental.usb.html#method-closeDevice",
     "chrome.experimental.usb.controlTransfer": "experimental.usb.html#method-controlTransfer",
     "chrome.experimental.usb.findDevice": "experimental.usb.html#method-findDevice",
     "chrome.experimental.usb.interruptTransfer": "experimental.usb.html#method-interruptTransfer",
     "chrome.experimental.usb.isochronousTransfer": "experimental.usb.html#method-isochronousTransfer",
     "chrome.experimental.usb.onEvent": "experimental.usb.html#event-onEvent",
+    "chrome.experimental.wm.onActiveWindowChanged": "experimental.wm.html#event-onActiveWindowChanged",
+    "chrome.experimental.wm.onWindowClosed": "experimental.wm.html#event-onWindowClosed",
+    "chrome.experimental.wm.onWindowCreated": "experimental.wm.html#event-onWindowCreated",
+    "chrome.experimental.wm.onWindowHidden": "experimental.wm.html#event-onWindowHidden",
+    "chrome.experimental.wm.onWindowShown": "experimental.wm.html#event-onWindowShown",
     "chrome.extension.connect": "extension.html#method-connect",
     "chrome.extension.getBackgroundPage": "extension.html#method-getBackgroundPage",
     "chrome.extension.getURL": "extension.html#method-getURL",
     "chrome.extension.getViews": "extension.html#method-getViews",
     "chrome.extension.isAllowedFileSchemeAccess": "extension.html#method-isAllowedFileSchemeAccess",
     "chrome.extension.isAllowedIncognitoAccess": "extension.html#method-isAllowedIncognitoAccess",
     "chrome.extension.onConnect": "extension.html#event-onConnect",
     "chrome.extension.onConnectExternal": "extension.html#event-onConnectExternal",
     "chrome.extension.onMessage": "extension.html#event-onMessage",
     "chrome.extension.onMessageExternal": "extension.html#event-onMessageExternal",
@@ skipping 2612 matching lines @@
         "manifest.json",
         "popup.html",
         "popup.js",
         "sample.css"
       ],
       "source_hash": "8e51dc3a9577065d22ce92f3c838edc5ceaf4e65",
       "zip_path": "examples/api/extension/isAllowedAccess.zip"
     }
   ]
 }