Implement virtual keyboard hiding.

chrome/common/extensions/api/experimental_input_virtual_keyboard.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "experimental.input.virtualKeyboard",
     "description": "none",
     "functions": [
       {
         "name": "insertText",
         "type": "function",
         "description": "Inserts text into the currently focused text field.",
         "parameters": [
           { "name": "text",
             "type": "string",
             "description": "The text that will be inserted."
           },
           { "type": "function",
             "name": "callback",
             "optional": true,
             "description": "Called when the insertion is completed.",
             "parameters": []
           }
         ]
+      },
+      {
+        "name": "hideKeyboard",

[bryeung, 2013/08/02 17:26:39]

We shouldn't be adding APIs to this namespace.  This needs to live in a new
dev-only (for now, I assume) API namespace for the virtual keyboard.

[SteveT, 2013/08/06 18:31:34]

I'm guessing this aligns with your discussion with kevers@ about his new key
event API? We probably want to come to the same consensus and land the code in
the same place.

I'll wait and see where those discussions land with Wez and yourself before
making a change here.

+        "type": "function",
+        "description": "Hides the virtual keyboard.",
+        "parameters": [
+          { "type": "function",
+            "name": "callback",
+            "optional": true,
+            "description": "Called when the keyboard is hidden.",
+            "parameters": []
+          }
+        ]
       }
     ]
   }
 ]