macviews: fix window miniaturization test with newer SDKs

This change:

1) Splits up NativeWidgetMacTest.MiniaturizeExternally, which was a bit too big;
2) Adds an override on NativeWidgetMacNSWindow of _canMiniaturize, which
   always allows Views windows to be miniaturized; this is the behavior that
   the rest of Views (and the tests) expect, and is what happened on older SDKs.

Bug: 780980
Change-Id: Ic3356787433d9325aa13f1e01a8165c4ddd07b0a
Reviewed-on: https://chromium-review.googlesource.com/c/1394010Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619656}

ui/views/widget/native_widget_mac_unittest.mm

@@ -599,10 +599,12 @@ TEST_F(NativeWidgetMacTest, MiniaturizeExternally) {
   EXPECT_EQ(3, view->paint_count());
 
   widget->CloseNow();
+}
 
+TEST_F(NativeWidgetMacTest, MiniaturizeFramelessWindow) {
   // Create a widget without a minimize button.
-  widget = CreateTopLevelFramelessPlatformWidget();
-  ns_window = widget->GetNativeWindow().GetNativeNSWindow();
+  Widget* widget = CreateTopLevelFramelessPlatformWidget();
+  NSWindow* ns_window = widget->GetNativeWindow().GetNativeNSWindow();
   widget->SetBounds(gfx::Rect(100, 100, 300, 300));
   widget->Show();
   EXPECT_FALSE(widget->IsMinimized());
@@ -613,6 +615,8 @@ TEST_F(NativeWidgetMacTest, MiniaturizeExternally) {
 
   // But this should work.
   widget->Minimize();
+  base::RunLoop().RunUntilIdle();
+
   EXPECT_TRUE(widget->IsMinimized());
 
   // Test closing while minimized.

ui/views_bridge_mac/native_widget_mac_nswindow.mm

@@ -271,6 +271,13 @@
   return touchBarDelegate_ ? [touchBarDelegate_ makeTouchBar] : nil;
 }
 
+// On newer SDKs, _canMiniaturize respects NSMiniaturizableWindowMask in the
+// window's styleMask. Views assumes that Widgets can always be minimized,
+// regardless of their window style, so override that behavior here.
+- (BOOL)_canMiniaturize {
+  return YES;
+}
+
 // CommandDispatchingWindow implementation.
 
 - (void)setCommandHandler:(id<UserInterfaceItemCommandHandler>)commandHandler {