MacViews: Fix Widget::GetAllChildWidgets(gfx::NativeView) for non-Widgets.

Currently GetAllChildWidgets only works for Widgets, but the API doesn't
require that. Passing a non-Widget allows the Widgets parented off a
Cocoa browser window to be easily obtained. This will help with testing
of browser dialogs.

BUG=654151

Review-Url: https://codereview.chromium.org/2535163002
Cr-Commit-Position: refs/heads/master@{#434911}

ui/views/widget/native_widget_mac.mm

@@ -689,8 +689,18 @@ void NativeWidgetPrivate::GetAllChildWidgets(gfx::NativeView native_view,
                                              Widget::Widgets* children) {
   BridgedNativeWidget* bridge =
       NativeWidgetMac::GetBridgeForNativeWindow([native_view window]);
-  if (!bridge)
+  if (!bridge) {
+    // The NSWindow is not itself a views::Widget, but it may have children that
+    // are. Support returning Widgets that are parented to the NSWindow, except:
+    // - Ignore requests for children of an NSView that is not a contentView.
+    // - We do not add a Widget for |native_view| to |children| (there is none).
+    if ([[native_view window] contentView] != native_view)
+      return;
+
+    for (NSWindow* native_child in [[native_view window] childWindows])
+      GetAllChildWidgets([native_child contentView], children);
     return;
+  }
 
   // If |native_view| is a subview of the contentView, it will share an
   // NSWindow, but will itself be a native child of the Widget. That is, adding
@@ -705,6 +715,10 @@ void NativeWidgetPrivate::GetAllChildWidgets(gfx::NativeView native_view,
   if (bridge->native_widget_mac()->GetWidget())
     children->insert(bridge->native_widget_mac()->GetWidget());
 
+  // When the NSWindow *is* a Widget, only consider child_windows(). I.e. do not
+  // look through -[NSWindow childWindows] as done for the (!bridge) case above.
+  // -childWindows does not support hidden windows, and anything in there which
+  // is not in child_windows() would have been added by AppKit.
   for (BridgedNativeWidget* child : bridge->child_windows())
     GetAllChildWidgets(child->ns_view(), children);
 }

ui/views/widget/native_widget_mac_unittest.mm

@@ -692,6 +692,11 @@ Widget* AttachPopupToNativeParent(NSWindow* native_parent) {
 // Tests creating a views::Widget parented off a native NSWindow.
 TEST_F(NativeWidgetMacTest, NonWidgetParent) {
   NSWindow* native_parent = MakeNativeParent();
+
+  Widget::Widgets children;
+  Widget::GetAllChildWidgets([native_parent contentView], &children);
+  EXPECT_TRUE(children.empty());
+
   Widget* child = AttachPopupToNativeParent(native_parent);
   TestWidgetObserver child_observer(child);
 
@@ -719,6 +724,10 @@ TEST_F(NativeWidgetMacTest, NonWidgetParent) {
             [[native_parent childWindows] objectAtIndex:0]);
   EXPECT_EQ(native_parent, [child->GetNativeWindow() parentWindow]);
 
+  Widget::GetAllChildWidgets([native_parent contentView], &children);
+  ASSERT_EQ(1u, children.size());
+  EXPECT_EQ(child, *children.begin());
+
   // Only non-toplevel Widgets are positioned relative to the parent, so the
   // bounds set above should be in screen coordinates.
   EXPECT_EQ(child_bounds, child->GetWindowBoundsInScreen());