Merge 173933

Merge 173933
> Make the cursor have separate mode for disabled mouse events and invisible.
> 
> This CL adds the following APIs.
> 
> * CursorClient::DisableMouseEvents: Makes mouse events stop being sent
> and hides the cursor if it is visible.
> (For now, DisableMouseEvents just clears the hover state and doesn't
> prevent mouse events from being generated, though).
> 
> * CursorClient::EnableMouseEvents: Makes mouse events start being sent
> and shows the cursor if it was hidden with DisableMouseEvents.
> 
> * CursorClient::HideCursor: Makes the cursor invisible. This changes
> only the cursor visibility and mouse events keep being sent even when
> the cursor is invisible.
> 
> * CursorClient::ShowCursor: Makes the cursor visible. This does not take
> effect When mouse events are disabled.
> 
> This CL just replaces the old usages of CursorClient::ShowCursor with
> the new APIs to retain existing behavior.
> I'll make another CL that uses these APIs in appropriate places.
> 
> BUG=153703
> TEST=CursorManagerTest.EnableDisableMouseEvents, CursorManagerTest.ShowAndEnable
> 
> Review URL: https://chromiumcodereview.appspot.com/11412315

TBR=mazda@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=177178