views: Make view::Views::GetPreferredSize() const.

ash/frame/custom_frame_view_ash.cc

Index: ash/frame/custom_frame_view_ash.cc
diff --git a/ash/frame/custom_frame_view_ash.cc b/ash/frame/custom_frame_view_ash.cc
index 68bc36a85c07d90cc63c8828636f1f0e7c8908c5..296dc3f12d7800ca015a2b4afe5af6a9e5fdc1d4 100644
--- a/ash/frame/custom_frame_view_ash.cc
+++ b/ash/frame/custom_frame_view_ash.cc
@@ -467,7 +467,7 @@ void CustomFrameViewAsh::UpdateWindowTitle() {
 ////////////////////////////////////////////////////////////////////////////////
 // CustomFrameViewAsh, views::View overrides:
 
-gfx::Size CustomFrameViewAsh::GetPreferredSize() {
+gfx::Size CustomFrameViewAsh::GetPreferredSize() const {
   gfx::Size pref = frame_->client_view()->GetPreferredSize();
   gfx::Rect bounds(0, 0, pref.width(), pref.height());
   return frame_->non_client_view()->GetWindowBoundsForClientBounds(
@@ -478,7 +478,7 @@ const char* CustomFrameViewAsh::GetClassName() const {
   return kViewClassName;
 }
 
-gfx::Size CustomFrameViewAsh::GetMinimumSize() {
+gfx::Size CustomFrameViewAsh::GetMinimumSize() const {
   gfx::Size min_client_view_size(frame_->client_view()->GetMinimumSize());
   return gfx::Size(
       std::max(header_view_->GetMinimumWidth(), min_client_view_size.width()),