Only perform dialog Layout() once during Widget::Init().

ui/views/widget/widget.cc

Index: ui/views/widget/widget.cc
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 6b0ecaeb15551b3fdc6c4e0cffc575df8cee5c8b..38ade374c65cfbb03616880c7d61507b3a5ba1a5 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -343,7 +343,12 @@ void Widget::Init(const InitParams& in_params) {
     // NonClientView to the RootView. This will cause everything to be parented.
     non_client_view_->set_client_view(widget_delegate_->CreateClientView(this));
     non_client_view_->SetOverlayView(widget_delegate_->CreateOverlayView());
-    SetContentsView(non_client_view_);
+
+    // Bypass the Layout() that happens in Widget::SetContentsView(). Layout()
+    // will occur after setting the initial bounds below. The RootView's size is
+    // not valid until that happens.
+    root_view_->SetContentsView(non_client_view_);
+
     // Initialize the window's icon and title before setting the window's
     // initial bounds; the frame view's preferred height may depend on the
     // presence of an icon or a title.
@@ -351,6 +356,12 @@ void Widget::Init(const InitParams& in_params) {
     UpdateWindowTitle();
     non_client_view_->ResetWindowControls();
     SetInitialBounds(params.bounds);
+
+    // Perform the initial layout. This handles the case where the size might
+    // not actually change when setting the initial bounds. If it did, child
+    // views won't have a dirty Layout state, so won't do any work.
+    root_view_->Layout();
+
     if (params.show_state == ui::SHOW_STATE_MAXIMIZED) {
       Maximize();
     } else if (params.show_state == ui::SHOW_STATE_MINIMIZED) {
@@ -457,7 +468,15 @@ void Widget::SetContentsView(View* view) {
   // Do not SetContentsView() again if it is already set to the same view.
   if (view == GetContentsView())
     return;
+
   root_view_->SetContentsView(view);
+
+  // Force a layout now, since the attached hierarchy won't be ready for the
+  // containing window's bounds. Note that we call Layout directly rather than
+  // calling the widget's size changed handler, since the RootView's bounds may
+  // not have changed, which will cause the Layout not to be done otherwise.
+  root_view_->Layout();
+
   if (non_client_view_ != view) {
     // |non_client_view_| can only be non-NULL here if RequiresNonClientView()
     // was true when the widget was initialized. Creating widgets with non