exo: Fix logic in |IsPhysicalKeyboardEnabled()|.

BUG=670247
TEST=Manual test by checking Configuration.hardKeyboardHidden when
     entering maximize mode.

Review-Url: https://codereview.chromium.org/2590893002
Cr-Commit-Position: refs/heads/master@{#439802}

components/exo/keyboard.cc

@@ -76,7 +76,7 @@ bool ConsumedByIme(Surface* focus, const ui::KeyEvent* event) {
 
 bool IsPhysicalKeyboardEnabled() {
   // The internal keyboard is enabled if maximize mode is not enabled.
-  if (WMHelper::GetInstance()->IsMaximizeModeWindowManagerEnabled())
+  if (!WMHelper::GetInstance()->IsMaximizeModeWindowManagerEnabled())
     return true;
 
   for (auto& keyboard :