Add {Lock,Unlock,Show,Hide}Cursor() to the window manager mojom.

services/ui/ws/display.h

Index: services/ui/ws/display.h
diff --git a/services/ui/ws/display.h b/services/ui/ws/display.h
index 98acc83ec341dd3de82475c22aa026a4a87b5a57..1ace44a2e574ad06c5239ebf5031590efe8a8585 100644
--- a/services/ui/ws/display.h
+++ b/services/ui/ws/display.h
@@ -149,8 +149,21 @@ class Display : public PlatformDisplayDelegate,
   // |display_root| being destroyed.
   void RemoveWindowManagerDisplayRoot(WindowManagerDisplayRoot* display_root);
 
+  // Sets the native cursor to |cursor|.
   void UpdateNativeCursor(const ui::CursorData& cursor);
 
+  // When the cursor is locked, changes to the cursor are queued up. Queued
+  // changes are performed atomically when the cursor is unlocked.
+  void LockCursor();
+  void UnlockCursor();
+
+  // Whether the cursor is visible on the display.
+  void ShowCursor();
+  void HideCursor();
+
+  // Sets a cursor globally, which overrides the per-window cursors.
+  void SetGlobalOverrideCursor(const base::Optional<ui::CursorData>& cursor);
+
   // mojom::WindowTreeHost:
   void SetSize(const gfx::Size& size) override;
   void SetTitle(const std::string& title) override;
@@ -167,6 +180,8 @@ class Display : public PlatformDisplayDelegate,
   using WindowManagerDisplayRootMap =
       std::map<UserId, WindowManagerDisplayRoot*>;
 
+  class CursorState;
+
   // Inits the necessary state once the display is ready.
   void InitWindowManagerDisplayRoots();
 
@@ -181,6 +196,9 @@ class Display : public PlatformDisplayDelegate,
   // pixels.
   void CreateRootWindow(const gfx::Size& size);
 
+  // Synchronizes |current_state_| with the platform display.
+  void SetPlatformCursor();
+
   // PlatformDisplayDelegate:
   ServerWindow* GetRootWindow() override;
   EventSink* GetEventSink() override;
@@ -218,8 +236,15 @@ class Display : public PlatformDisplayDelegate,
   // external window mode this will be invalid.
   display::Display display_;
 
-  // The last cursor set. Used to track whether we need to change the cursor.
-  ui::CursorData last_cursor_;
+  // Number of times LockCursor() has been invoked without a corresponding
+  // UnlockCursor().
+  int cursor_lock_count_ = 0u;
+
+  // The current state of the cursor.
+  std::unique_ptr<CursorState> current_state_;
+
+  // The cursor state to restore when the cursor is unlocked.
+  std::unique_ptr<CursorState> state_on_unlock_;
 
   ServerWindowTracker activation_parents_;