Add power-user keyboard mode for ChromeOS with Search key acting as a typical Fn key.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index b51ab860521abada067df9c58393ae2cf41a4a03..2abc2d8068822a94118b547ddda2a246176d05b2 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -943,6 +943,13 @@ const Experiment kExperiments[] = {
     kOsCrOS,
     SINGLE_VALUE_TYPE(switches::kFileManagerPackaged),
   },
+  {
+    "enable-chromeos-function-key",
+    IDS_FLAGS_ENABLE_CHROMEOS_FUNCTION_KEY_NAME,
+    IDS_FLAGS_ENABLE_CHROMEOS_FUNCTION_KEY_DESCRIPTION,
+    kOsCrOS,
+    SINGLE_VALUE_TYPE(switches::kEnableChromeOSFunctionKey),
+  },
 #endif
   {
     "enable-views-textfield",