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

ui/views/controls/scrollbar/native_scroll_bar_views.cc

Index: ui/views/controls/scrollbar/native_scroll_bar_views.cc
diff --git a/ui/views/controls/scrollbar/native_scroll_bar_views.cc b/ui/views/controls/scrollbar/native_scroll_bar_views.cc
index a8402e5c65591d0b837f333f89e6c73785619e4a..b4f83ccdf7b932e7942e6885e07bac762f73d7c0 100644
--- a/ui/views/controls/scrollbar/native_scroll_bar_views.cc
+++ b/ui/views/controls/scrollbar/native_scroll_bar_views.cc
@@ -32,7 +32,7 @@ class ScrollBarButton : public BaseScrollBarButton {
   ScrollBarButton(ButtonListener* listener, Type type);
   virtual ~ScrollBarButton();
 
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual const char* GetClassName() const OVERRIDE {
     return "ScrollBarButton";
   }
@@ -54,7 +54,7 @@ class ScrollBarThumb : public BaseScrollBarThumb {
   explicit ScrollBarThumb(BaseScrollBar* scroll_bar);
   virtual ~ScrollBarThumb();
 
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual const char* GetClassName() const OVERRIDE {
     return "ScrollBarThumb";
   }
@@ -83,7 +83,7 @@ ScrollBarButton::ScrollBarButton(ButtonListener* listener, Type type)
 ScrollBarButton::~ScrollBarButton() {
 }
 
-gfx::Size ScrollBarButton::GetPreferredSize() {
+gfx::Size ScrollBarButton::GetPreferredSize() const {
   return GetNativeTheme()->GetPartSize(GetNativeThemePart(),
                                        GetNativeThemeState(),
                                        GetNativeThemeParams());
@@ -164,7 +164,7 @@ ScrollBarThumb::ScrollBarThumb(BaseScrollBar* scroll_bar)
 ScrollBarThumb::~ScrollBarThumb() {
 }
 
-gfx::Size ScrollBarThumb::GetPreferredSize() {
+gfx::Size ScrollBarThumb::GetPreferredSize() const {
   return GetNativeTheme()->GetPartSize(GetNativeThemePart(),
                                        GetNativeThemeState(),
                                        GetNativeThemeParams());
@@ -292,7 +292,7 @@ void NativeScrollBarViews::OnPaint(gfx::Canvas* canvas) {
   GetNativeTheme()->Paint(canvas->sk_canvas(), part_, state_, bounds, params_);
 }
 
-gfx::Size NativeScrollBarViews::GetPreferredSize() {
+gfx::Size NativeScrollBarViews::GetPreferredSize() const {
   const ui::NativeTheme* theme = native_scroll_bar_->GetNativeTheme();
   if (native_scroll_bar_->IsHorizontal())
     return gfx::Size(0, GetHorizontalScrollBarHeight(theme));