wm: Make WM_MOVE_PANEL use top-right coordinates.

src/platform/window_manager/mock_chrome.h

Index: src/platform/window_manager/mock_chrome.h
diff --git a/src/platform/window_manager/mock_chrome.h b/src/platform/window_manager/mock_chrome.h
index 596471d4fab1dd5a15aff3296e1a483029be70ed..e0339eedb34689115a1a555f5aa74962ceb0a821 100644
--- a/src/platform/window_manager/mock_chrome.h
+++ b/src/platform/window_manager/mock_chrome.h
@@ -293,11 +293,11 @@ class PanelTitlebar : public Gtk::Window {
   // Is the mouse button currently down?
   bool mouse_down_;
 
-  // Cursor's absolute position when the mouse button was pressed.
+  // Pointer's absolute position when the mouse button was pressed.
   int mouse_down_abs_x_;
   int mouse_down_abs_y_;
 
-  // Cursor's offset from the upper-left corner of the titlebar when the
+  // Pointer's offset from the upper-right corner of the titlebar when the
   // mouse button was pressed.
   int mouse_down_offset_x_;
   int mouse_down_offset_y_;