Wire up an api to darken screen for accessibility

chrome/common/extensions/api/automation_internal.idl

Index: chrome/common/extensions/api/automation_internal.idl
diff --git a/chrome/common/extensions/api/automation_internal.idl b/chrome/common/extensions/api/automation_internal.idl
index e6b1e8b10ffa19ad310b58194b5e7849f4f0bd33..132193c76b1e30df122a65e0fae4ae2e14dd5ddb 100644
--- a/chrome/common/extensions/api/automation_internal.idl
+++ b/chrome/common/extensions/api/automation_internal.idl
@@ -40,7 +40,8 @@ namespace automationInternal {
     startDuckingMedia,
     stopDuckingMedia,
     suspendMedia,
-    showContextMenu
+    showContextMenu,
+    toggleDarkenScreen
   };
 
   // Arguments required for all actions supplied to performAction.
@@ -78,6 +79,12 @@ namespace automationInternal {
     long maxHeight;
   };
 
+  // Arguments for the toggleDarkenScreen action supplied to performAction.
+  dictionary ToggleDarkenScreenParams {
+    // Whether to darken or undarken screen.
+    boolean darkenScreen;

[dmazzoni, 2017/03/22 21:40:48]

Passing a bool doesn't really match "toggle". How about calling the
action setScreenDarkening instead?

+  };
+
   // Returns the accessibility tree id of the web contents who's accessibility
   // was enabled using enableTab().
   callback EnableTabCallback = void(long tree_id);