[Win] Update HWND style when SizeConstraintsChanged.

ui/views/widget/widget_hwnd_utils.cc

Index: ui/views/widget/widget_hwnd_utils.cc
diff --git a/ui/views/widget/widget_hwnd_utils.cc b/ui/views/widget/widget_hwnd_utils.cc
index ac313bb74c89967a7578605bf0e9eda80330d020..f4a50dff2e06af867f4d43100e61501af04cd30a 100644
--- a/ui/views/widget/widget_hwnd_utils.cc
+++ b/ui/views/widget/widget_hwnd_utils.cc
@@ -81,14 +81,17 @@ void CalculateWindowStylesFromInitParams(
       }
       // Else, no break. Fall through to TYPE_WINDOW.
     case Widget::InitParams::TYPE_WINDOW: {
-      *style |= WS_SYSMENU | WS_CAPTION;
-      bool can_resize = widget_delegate->CanResize();
-      bool can_maximize = widget_delegate->CanMaximize();
-      if (can_maximize) {
-        *style |= WS_OVERLAPPEDWINDOW;
-      } else if (can_resize || params.remove_standard_frame) {
-        *style |= WS_OVERLAPPED | WS_THICKFRAME;
-      }
+      // WS_OVERLAPPEDWINDOW is equivalent to:
+      //   WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU |
+      //   WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX
+      *style |= WS_OVERLAPPEDWINDOW;
+      if (!widget_delegate->CanMaximize())
+        *style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX);

[sky, 2014/09/18 14:27:09]

Why remove the minimize button if the window can't maximize?

[jackhou1, 2014/09/18 23:28:35]

Hah, I was hoping you would know. There's this bug, http://crbug.com/341010,
referenced in HWNDMessageHandler::OnInitMenu. Essentially we want to disable the
Minimize in the right click menu to prevent certain dialog boxes from being
minimizable.

But it seems that throughout Windows and CrOS, we always hide the minimize
button when a window is not maximizable. Any idea who might know more about
this?

This CL maintains the existing semantics. If I can't find out why we do this,
I'll put together another CL that changes it.

+      if (!widget_delegate->CanResize())
+        *style &= ~(WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX);
+      if (params.remove_standard_frame)
+        *style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX);
+
       if (native_widget_delegate->IsDialogBox()) {
         *style |= DS_MODALFRAME;
         // NOTE: Turning this off means we lose the close button, which is bad.