Wire up an api to darken screen for accessibility

chrome/browser/accessibility/accessibility_extension_api.cc

Index: chrome/browser/accessibility/accessibility_extension_api.cc
diff --git a/chrome/browser/accessibility/accessibility_extension_api.cc b/chrome/browser/accessibility/accessibility_extension_api.cc
index 66aa8e9df78b2e43845e78c32d411a8f01d2600e..504c126139a40723e0b530b7cad28541d77ef47c 100644
--- a/chrome/browser/accessibility/accessibility_extension_api.cc
+++ b/chrome/browser/accessibility/accessibility_extension_api.cc
@@ -30,6 +30,9 @@
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
 #include "chrome/browser/chromeos/ui/accessibility_focus_ring_controller.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/power_manager_client.h"
+
 using chromeos::AccessibilityFocusRingController;
 #endif
 
@@ -129,3 +132,24 @@ AccessibilityPrivateSetKeyboardListenerFunction::Run() {
 
   return RespondNow(Error(kErrorNotSupported));
 }
+
+ExtensionFunction::ResponseAction
+AccessibilityPrivateDarkenScreenFunction::Run() {
+  ChromeExtensionFunctionDetails details(this);
+  CHECK(extension());
+
+#if defined(OS_CHROMEOS)
+  bool darken;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetBoolean(0, &darken));
+  chromeos::PowerManagerClient* client =
+      chromeos::DBusThreadManager::Get()->GetPowerManagerClient();
+
+  // Called twice to ensure the cros end of the dbus message is in a good
+  // state.
+  client->SetBacklightsForcedOff(!darken);
+  client->SetBacklightsForcedOff(darken);
+  return RespondNow(NoArguments());
+#endif  // defined OS_CHROMEOS
+
+  return RespondNow(Error(kErrorNotSupported));
+}