Adding fullscreen mode access to chrome.fileBrowserPrivate API.

chrome/common/extensions/api/fileBrowserPrivate.json

Index: chrome/common/extensions/api/fileBrowserPrivate.json
diff --git a/chrome/common/extensions/api/fileBrowserPrivate.json b/chrome/common/extensions/api/fileBrowserPrivate.json
index d2935986c1ec218cfedbe021941c738c6f173ee1..a365827e55d0a994e0e4f9c80d1309871af6df27 100644
--- a/chrome/common/extensions/api/fileBrowserPrivate.json
+++ b/chrome/common/extensions/api/fileBrowserPrivate.json
@@ -530,6 +530,29 @@
             "description": "Device's mount path."
           }
         ]
+      },
+      {
+        "name": "toggleFullscreen",
+        "description": "Switches fullscreen mode on/off for the File Browser.",
+        "parameters": []
+      },
+      {
+        "name": "isFullscreen",
+        "description": "Checks if the browser is in fullscreen mode.",
+        "parameters": [
+          {
+            "name": "callback",
+            "type": "function",
+            "optional": false,
+            "parameters": [
+              {
+                "name" : "result",
+                "type": "boolean",
+                "description": "Whether the browser is in fullscreen mode."
+              }
+            ]
+          }
+        ]
       }
     ],
     "events": [