fix: correctly enable and disable windows on Windows and Linux (backport: 3-0-x) (#15255)

* fix: correctly enable and disable windows

* Move has_child_modal_ to NativeWindowViews

* Track modal children as an int instead of a bool

* Use correct types

* Move Increment/DecrementChildModals to NativeWindowViews

* Use parent() in NativeWindowViews

* Add test for not enabling disabled parent when modal child closes

atom/browser/native_window_views.h

@@ -129,6 +129,9 @@ class NativeWindowViews : public NativeWindow,
 
   void UpdateDraggableRegions(std::unique_ptr<SkRegion> region);
 
+  void IncrementChildModals();
+  void DecrementChildModals();
+
 #if defined(OS_WIN)
   void SetIcon(HICON small_icon, HICON app_icon);
 #elif defined(USE_X11)
@@ -185,6 +188,10 @@ class NativeWindowViews : public NativeWindow,
                                         LPARAM l_param);
 #endif
 
+  // Enable/disable:
+  bool ShouldBeEnabled();
+  void SetEnabledInternal(bool enabled);
+
   // NativeWindow:
   void HandleKeyboardEvent(
       content::WebContents*,
@@ -268,8 +275,11 @@ class NativeWindowViews : public NativeWindow,
   // has to been explicitly provided.
   std::unique_ptr<SkRegion> draggable_region_;  // used in custom drag.
 
-  // How many times the Disable has been called.
-  int disable_count_ = 0;
+  // Whether the window should be enabled based on user calls to SetEnabled()
+  bool is_enabled_ = true;
+  // How many modal children this window has;
+  // used to determine enabled state
+  unsigned int num_modal_children_ = 0;
 
   bool use_content_size_ = false;
   bool movable_ = true;