Add a virtual keyboard webui at chrome://keyboard/

chrome/common/extensions/manifest_url_handler.cc

Index: chrome/common/extensions/manifest_url_handler.cc
diff --git a/chrome/common/extensions/manifest_url_handler.cc b/chrome/common/extensions/manifest_url_handler.cc
index 690cc03e21a78851a1062d0c9f856a2432708e61..20b399a81881ae1fe2e4abb5ef4b5224b662daa2 100644
--- a/chrome/common/extensions/manifest_url_handler.cc
+++ b/chrome/common/extensions/manifest_url_handler.cc
@@ -22,6 +22,10 @@
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(USE_AURA)
+#include "ui/keyboard/keyboard_constants.h"
+#endif
+
 namespace keys = extension_manifest_keys;
 namespace errors = extension_manifest_errors;
 
@@ -276,6 +280,9 @@ bool URLOverridesHandler::Parse(Extension* extension, string16* error) {
                    !(extension->location() == Manifest::COMPONENT &&
                      page == chrome::kChromeUIFileManagerHost));
 #endif
+#if defined(USE_AURA)
+    is_override = (is_override && page != keyboard::kKeyboardWebUIHost);
+#endif
 
     if (is_override || !iter.value().GetAsString(&val)) {
       *error = ASCIIToUTF16(errors::kInvalidChromeURLOverrides);