Implement large cursors in Mushrome.

services/ui/public/interfaces/window_manager.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module ui.mojom;
 
 import "cc/ipc/frame_sink_id.mojom";
 import "cc/ipc/local_surface_id.mojom";
 import "services/ui/public/interfaces/cursor/cursor.mojom";
 import "services/ui/public/interfaces/event_matcher.mojom";
@@ skipping 301 matching lines @@
   WmSetNonClientCursor(uint32 window_id, CursorData cursor);
 
   // Locks and unlocks the cursor globally. Used during window management tasks
   // where the cursor shouldn't change.
   WmLockCursor();
   WmUnlockCursor();
 
   // Shows and hides the cursor globally. Used during window management tasks.
   WmSetCursorVisible(bool visible);
 
+  // Sets whether we're using normal or large cursors.
+  WmSetCursorSet(CursorSet cursor_set);

[Tom Sepez, 2017/06/23 01:10:48]

What happens if a bad renderer changes to large (or vice versa) and continues to
use normal cursor methods (or vice versa)? 

[Elliot Glaysher, 2017/06/23 19:30:38]

I'm not sure I understand the question. This method is only available to the
window manager.

Let's say you have an untrusted renderer that sets its window's cursor to GRAB.
Mus keeps track of that data and will change the system cursor to GRAB when the
pointer is over that window. But what cursor will it use? A 1x cursor or a 2x?
That's what this method controls.

What happens if the renderer sets the cursor over its window to a small image
when using the large cursor set? It uses the renderer supplied data. This method
just controls selecting the size of inbuilt named cursors.

+
   // Sets a global cursor which overrides per-window cursors. Pass null to
   // clear.
   WmSetGlobalOverrideCursor(CursorData? cursor);
 
   // Moves the cursor to the given location on the given display.
   WmMoveCursorToDisplayLocation(gfx.mojom.Point display_pixels,
                                 int64 display_id);
 
   // Response from WmCreateTopLevelWindow() informing the client of the id for
   // the new window.
   OnWmCreatedTopLevelWindow(uint32 change_id, uint32 window_id);
 
   // See description in WindowManager::OnAccelerator(). |ack_id| is the value
   // that was passed to OnAccelerator(). If the accelerator is a pre-target
   // handler and |event_result| is UNHANDLED, then |properties| is added to
   // the KeyEvent that is dispatched to the client with the focused window.
   OnAcceleratorAck(uint32 ack_id,
                    EventResult event_result,
                    map<string, array<uint8>> properties);
 };