Add a pref checkbox to enable/disable screen lock for ChromeOs.

chrome/browser/chromeos/cros/power_library.cc

Index: chrome/browser/chromeos/cros/power_library.cc
diff --git a/chrome/browser/chromeos/cros/power_library.cc b/chrome/browser/chromeos/cros/power_library.cc
index 220cd4e353666b373d009535ca415a307e5fa9cf..85c5e9a26771963f0560b6686ad82918fd81dfea 100644
--- a/chrome/browser/chromeos/cros/power_library.cc
+++ b/chrome/browser/chromeos/cros/power_library.cc
@@ -59,6 +59,22 @@ class PowerLibraryImpl : public PowerLibrary {
     return base::TimeDelta::FromSeconds(status_.battery_time_to_full);
   }
 
+  virtual void EnableScreenLock(bool enable) {
+    if (!CrosLibrary::Get()->EnsureLoaded())
+      return;
+
+    // Make sure we run on FILE thread becuase chromeos::EnableScreenLock
+    // would write power manager config file to disk.
+    if (!ChromeThread::CurrentlyOn(ChromeThread::FILE)) {
+      ChromeThread::PostTask(
+          ChromeThread::FILE, FROM_HERE,
+          NewRunnableMethod(this, &PowerLibraryImpl::EnableScreenLock, enable));
+      return;
+    }
+
+    chromeos::EnableScreenLock(enable);
+  }
+
  private:
   static void PowerStatusChangedHandler(void* object,
       const chromeos::PowerStatus& status) {
@@ -119,6 +135,7 @@ class PowerLibraryStubImpl : public PowerLibrary {
   base::TimeDelta battery_time_to_full() const {
     return base::TimeDelta::FromSeconds(0);
   }
+  virtual void EnableScreenLock(bool enable) {}
 };
 
 // static