Refactor window impl of scroll bar for future linux implementation.

 - Changed NativeScrollBar to use native wrapper
 - Added NativeScrollBarWapper for NativeScrollBar to delegate operations to
   native control.
 - Moved window specific impl in NativeScrollBar to NativeScrollBarWin class
   which is a native wrapper.
 - Fixed a bug in native_control_win. need to call Layout when
   view visibility is changed after native contol is created.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/214048

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27013 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 544 insertions, 327 deletions

diff --git a/views/controls/native_control_win.cc b/views/controls/native_control_win.cc
index 406b470..9f4d2d6 100644
--- a/views/controls/native_control_win.cc
+++ b/views/controls/native_control_win.cc
@@ -78,7 +78,12 @@ void NativeControlWin::VisibilityChanged(View* starting_from, bool is_visible) {
     Detach();
     DestroyWindow(hwnd);
   } else if (!native_view()) {
-    CreateNativeControl();
+    if (GetWidget())
+      CreateNativeControl();
+  } else {
+    // The view becomes visible after native control is created.
+    // Layout now.
+    Layout();
   }
 }
 
diff --git a/views/controls/scrollbar/native_scroll_bar.cc b/views/controls/scrollbar/native_scroll_bar.cc
index 5ec60f3..39a9120 100644
--- a/views/controls/scrollbar/native_scroll_bar.cc
+++ b/views/controls/scrollbar/native_scroll_bar.cc
@@ -8,326 +8,94 @@
 #include <string>
 
 #include "base/message_loop.h"
-#include "base/window_impl.h"
-#include "views/controls/native/native_view_host.h"
+#include "views/controls/scrollbar/native_scroll_bar_wrapper.h"
 #include "views/widget/widget.h"
 
 namespace views {
 
-/////////////////////////////////////////////////////////////////////////////
-//
-// ScrollBarContainer
-//
-// Since windows scrollbars only send notifications to their parent hwnd, we
-// use instances of this class to wrap native scrollbars.
-//
-/////////////////////////////////////////////////////////////////////////////
-class ScrollBarContainer : public base::WindowImpl {
- public:
-  explicit ScrollBarContainer(ScrollBar* parent) : parent_(parent),
-                                                   scrollbar_(NULL) {
-    set_window_style(WS_CHILD);
-    Init(parent->GetWidget()->GetNativeView(), gfx::Rect());
-    ShowWindow(hwnd(), SW_SHOW);
-  }
-
-  virtual ~ScrollBarContainer() {
-  }
-
-  BEGIN_MSG_MAP_EX(ScrollBarContainer);
-    MSG_WM_CREATE(OnCreate);
-    MSG_WM_ERASEBKGND(OnEraseBkgnd);
-    MSG_WM_PAINT(OnPaint);
-    MSG_WM_SIZE(OnSize);
-    MSG_WM_HSCROLL(OnHorizScroll);
-    MSG_WM_VSCROLL(OnVertScroll);
-  END_MSG_MAP();
-
-  HWND GetScrollBarHWND() {
-    return scrollbar_;
-  }
-
-  // Invoked when the scrollwheel is used
-  void ScrollWithOffset(int o) {
-    SCROLLINFO si;
-    si.cbSize = sizeof(si);
-    si.fMask = SIF_POS;
-    GetScrollInfo(scrollbar_, SB_CTL, &si);
-    int pos = si.nPos - o;
-
-    if (pos < parent_->GetMinPosition())
-      pos = parent_->GetMinPosition();
-    else if (pos > parent_->GetMaxPosition())
-      pos = parent_->GetMaxPosition();
-
-    ScrollBarController* sbc = parent_->GetController();
-    sbc->ScrollToPosition(parent_, pos);
-
-    si.nPos = pos;
-    si.fMask = SIF_POS;
-    SetScrollInfo(scrollbar_, SB_CTL, &si, TRUE);
-  }
-
- private:
-
-  LRESULT OnCreate(LPCREATESTRUCT create_struct) {
-    scrollbar_ = CreateWindow(L"SCROLLBAR", L"",
-                              WS_CHILD | (parent_->IsHorizontal() ?
-                                          SBS_HORZ : SBS_VERT),
-                              0, 0, parent_->width(), parent_->height(),
-                              hwnd(), NULL, NULL, NULL);
-    ShowWindow(scrollbar_, SW_SHOW);
-    return 1;
-  }
-
-  LRESULT OnEraseBkgnd(HDC dc) {
-    return 1;
-  }
-
-  void OnPaint(HDC ignore) {
-    PAINTSTRUCT ps;
-    HDC dc = BeginPaint(hwnd(), &ps);
-    EndPaint(hwnd(), &ps);
-  }
-
-  void OnSize(int type, const CSize& sz) {
-    SetWindowPos(scrollbar_,
-                 0, 0, 0, sz.cx, sz.cy,
-                 SWP_DEFERERASE | SWP_NOACTIVATE | SWP_NOCOPYBITS |
-                 SWP_NOOWNERZORDER | SWP_NOSENDCHANGING | SWP_NOZORDER);
-  }
-
-  void OnScroll(int code, HWND source, bool is_horizontal) {
-    int pos;
-
-    if (code == SB_ENDSCROLL) {
-      return;
-    }
-
-    // If we receive an event from the scrollbar, make the view
-    // component focused so we actually get mousewheel events.
-    if (source != NULL) {
-      Widget* widget = parent_->GetWidget();
-      if (widget && widget->GetNativeView() != GetFocus()) {
-        parent_->RequestFocus();
-      }
-    }
-
-    SCROLLINFO si;
-    si.cbSize = sizeof(si);
-    si.fMask = SIF_POS | SIF_TRACKPOS;
-    GetScrollInfo(scrollbar_, SB_CTL, &si);
-    pos = si.nPos;
-
-    ScrollBarController* sbc = parent_->GetController();
-
-    switch (code) {
-      case SB_BOTTOM:  // case SB_RIGHT:
-        pos = parent_->GetMaxPosition();
-        break;
-      case SB_TOP:  // case SB_LEFT:
-        pos = parent_->GetMinPosition();
-        break;
-      case SB_LINEDOWN:  //  case SB_LINERIGHT:
-        pos += sbc->GetScrollIncrement(parent_, false, true);
-        pos = std::min(parent_->GetMaxPosition(), pos);
-        break;
-      case SB_LINEUP:  //  case SB_LINELEFT:
-        pos -= sbc->GetScrollIncrement(parent_, false, false);
-        pos = std::max(parent_->GetMinPosition(), pos);
-        break;
-      case SB_PAGEDOWN:  //  case SB_PAGERIGHT:
-        pos += sbc->GetScrollIncrement(parent_, true, true);
-        pos = std::min(parent_->GetMaxPosition(), pos);
-        break;
-      case SB_PAGEUP:  // case SB_PAGELEFT:
-        pos -= sbc->GetScrollIncrement(parent_, true, false);
-        pos = std::max(parent_->GetMinPosition(), pos);
-        break;
-      case SB_THUMBPOSITION:
-      case SB_THUMBTRACK:
-        pos = si.nTrackPos;
-        if (pos < parent_->GetMinPosition())
-          pos = parent_->GetMinPosition();
-        else if (pos > parent_->GetMaxPosition())
-          pos = parent_->GetMaxPosition();
-        break;
-      default:
-        break;
-    }
-
-    sbc->ScrollToPosition(parent_, pos);
-
-    si.nPos = pos;
-    si.fMask = SIF_POS;
-    SetScrollInfo(scrollbar_, SB_CTL, &si, TRUE);
-
-    // Note: the system scrollbar modal loop doesn't give a chance
-    // to our message_loop so we need to call DidProcessMessage()
-    // manually.
-    //
-    // Sadly, we don't know what message has been processed. We may
-    // want to remove the message from DidProcessMessage()
-    MSG dummy;
-    dummy.hwnd = NULL;
-    dummy.message = 0;
-    MessageLoopForUI::current()->DidProcessMessage(dummy);
-  }
-
-  // note: always ignore 2nd param as it is 16 bits
-  void OnHorizScroll(int n_sb_code, int ignore, HWND source) {
-    OnScroll(n_sb_code, source, true);
-  }
+// static
+const char NativeScrollBar::kViewClassName[] = "views/NativeScrollBar";
 
-  // note: always ignore 2nd param as it is 16 bits
-  void OnVertScroll(int n_sb_code, int ignore, HWND source) {
-    OnScroll(n_sb_code, source, false);
-  }
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBar, public:
+NativeScrollBar::NativeScrollBar(bool is_horizontal)
+    : ScrollBar(is_horizontal),
+      native_wrapper_(NULL) {
+}
 
+NativeScrollBar::~NativeScrollBar() {
+}
 
+// static
+int NativeScrollBar::GetHorizontalScrollBarHeight() {
+  return NativeScrollBarWrapper::GetHorizontalScrollBarHeight();
+}
 
-  ScrollBar* parent_;
-  HWND scrollbar_;
-};
+// static
+int NativeScrollBar::GetVerticalScrollBarWidth() {
+  return NativeScrollBarWrapper::GetVerticalScrollBarWidth();
+}
 
-NativeScrollBar::NativeScrollBar(bool is_horiz)
-  : sb_view_(NULL),
-    sb_container_(NULL),
-    ScrollBar(is_horiz) {
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBar, View overrides:
+gfx::Size NativeScrollBar::GetPreferredSize() {
+  if (native_wrapper_)
+    return native_wrapper_->GetView()->GetPreferredSize();
+  return gfx::Size();
 }
 
-NativeScrollBar::~NativeScrollBar() {
-  if (sb_container_) {
-    // We always destroy the scrollbar container explicitly to cover all
-    // cases including when the container is no longer connected to a
-    // widget tree.
-    DestroyWindow(sb_container_->hwnd());
-    delete sb_container_;
-  }
+void NativeScrollBar::Layout() {
+  if (native_wrapper_)
+    native_wrapper_->GetView()->Layout();
 }
 
 void NativeScrollBar::ViewHierarchyChanged(bool is_add, View *parent,
                                            View *child) {
   Widget* widget;
-  if (is_add && (widget = GetWidget()) && !sb_view_) {
-    sb_view_ = new NativeViewHost;
-    AddChildView(sb_view_);
-    sb_container_ = new ScrollBarContainer(this);
-    sb_view_->Attach(sb_container_->hwnd());
-    Layout();
+  if (is_add && !native_wrapper_ && (widget = GetWidget())) {
+    native_wrapper_ = NativeScrollBarWrapper::CreateWrapper(this);
+    AddChildView(native_wrapper_->GetView());
   }
 }
 
-void NativeScrollBar::Layout() {
-  if (sb_view_)
-    sb_view_->SetBounds(GetLocalBounds(true));
+std::string NativeScrollBar::GetClassName() const {
+  return kViewClassName;
 }
 
-gfx::Size NativeScrollBar::GetPreferredSize() {
-  if (IsHorizontal())
-    return gfx::Size(0, GetLayoutSize());
-  return gfx::Size(GetLayoutSize(), 0);
+// Overridden from View for keyboard UI.
+bool NativeScrollBar::OnKeyPressed(const KeyEvent& event) {
+  if (!native_wrapper_)
+    return false;
+  return native_wrapper_->GetView()->OnKeyPressed(event);
+}
+
+bool NativeScrollBar::OnMouseWheel(const MouseWheelEvent& event) {
+  if (!native_wrapper_)
+    return false;
+  return native_wrapper_->GetView()->OnMouseWheel(event);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBar, ScrollBar overrides:
 void NativeScrollBar::Update(int viewport_size,
                              int content_size,
                              int current_pos) {
   ScrollBar::Update(viewport_size, content_size, current_pos);
-  if (!sb_container_)
-    return;
 
-  if (content_size < 0)
-    content_size = 0;
-
-  if (current_pos < 0)
-    current_pos = 0;
-
-  if (current_pos > content_size)
-    current_pos = content_size;
-
-  SCROLLINFO si;
-  si.cbSize = sizeof(si);
-  si.fMask = SIF_DISABLENOSCROLL | SIF_POS | SIF_RANGE | SIF_PAGE;
-  si.nMin = 0;
-  si.nMax = content_size;
-  si.nPos = current_pos;
-  si.nPage = viewport_size;
-  SetScrollInfo(sb_container_->GetScrollBarHWND(), SB_CTL, &si, TRUE);
+  if (native_wrapper_)
+    native_wrapper_->Update(viewport_size, content_size, current_pos);
 }
 
 int NativeScrollBar::GetLayoutSize() const {
-  return GetSystemMetrics(IsHorizontal() ? SM_CYHSCROLL : SM_CYVSCROLL);
+  return IsHorizontal() ?
+      GetHorizontalScrollBarHeight() : GetVerticalScrollBarWidth();
 }
 
 int NativeScrollBar::GetPosition() const {
-  SCROLLINFO si;
-  si.cbSize = sizeof(si);
-  si.fMask = SIF_POS;
-  GetScrollInfo(sb_container_->GetScrollBarHWND(), SB_CTL, &si);
-  return si.nPos;
-}
-
-bool NativeScrollBar::OnMouseWheel(const MouseWheelEvent& e) {
-  if (!sb_container_) {
-    return false;
-  }
-
-  sb_container_->ScrollWithOffset(e.GetOffset());
-  return true;
-}
-
-bool NativeScrollBar::OnKeyPressed(const KeyEvent& event) {
-  if (!sb_container_) {
-    return false;
-  }
-  int code = -1;
-  switch (event.GetCharacter()) {
-    case VK_UP:
-      if (!IsHorizontal())
-        code = SB_LINEUP;
-      break;
-    case VK_PRIOR:
-      code = SB_PAGEUP;
-      break;
-    case VK_NEXT:
-      code = SB_PAGEDOWN;
-      break;
-    case VK_DOWN:
-      if (!IsHorizontal())
-        code = SB_LINEDOWN;
-      break;
-    case VK_HOME:
-      code = SB_TOP;
-      break;
-    case VK_END:
-      code = SB_BOTTOM;
-      break;
-    case VK_LEFT:
-      if (IsHorizontal())
-        code = SB_LINELEFT;
-      break;
-    case VK_RIGHT:
-      if (IsHorizontal())
-        code = SB_LINERIGHT;
-      break;
-  }
-  if (code != -1) {
-    SendMessage(sb_container_->hwnd(),
-                IsHorizontal() ? WM_HSCROLL : WM_VSCROLL,
-                MAKELONG(static_cast<WORD>(code), 0), 0L);
-    return true;
-  }
-  return false;
-}
-
-// static
-int NativeScrollBar::GetHorizontalScrollBarHeight() {
-  return GetSystemMetrics(SM_CYHSCROLL);
-}
-
-// static
-int NativeScrollBar::GetVerticalScrollBarWidth() {
-  return GetSystemMetrics(SM_CXVSCROLL);
+  if (!native_wrapper_)
+    return 0;
+  return native_wrapper_->GetPosition();
 }
 
 }  // namespace views
+
diff --git a/views/controls/scrollbar/native_scroll_bar.h b/views/controls/scrollbar/native_scroll_bar.h
index 85a0453..6595a09 100644
--- a/views/controls/scrollbar/native_scroll_bar.h
+++ b/views/controls/scrollbar/native_scroll_bar.h
@@ -1,67 +1,57 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLLBAR_H_
-#define VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLLBAR_H_
+#ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_H_
+#define VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_H_
 
-#include "build/build_config.h"
+#include <string>
 
 #include "views/controls/scrollbar/scroll_bar.h"
+#include "views/view.h"
 
 namespace views {
 
-class NativeViewHost;
-class ScrollBarContainer;
-
-/////////////////////////////////////////////////////////////////////////////
-//
-// NativeScrollBar
-//
-// A View subclass that wraps a Native Windows scrollbar control.
-//
-// A scrollbar is either horizontal or vertical.
-//
-/////////////////////////////////////////////////////////////////////////////
+class NativeScrollBarWrapper;
+
+// The NativeScrollBar class is a scrollbar that uses platform's
+// native control.
 class NativeScrollBar : public ScrollBar {
  public:
+  // The scroll-bar's class name.
+  static const char kViewClassName[];
 
-  // Create new scrollbar, either horizontal or vertical
+  // Create new scrollbar, either horizontal or vertical.
   explicit NativeScrollBar(bool is_horiz);
   virtual ~NativeScrollBar();
 
-  // Overridden for layout purpose
-  virtual void Layout();
+  // Return the system sizes.
+  static int GetHorizontalScrollBarHeight();
+  static int GetVerticalScrollBarWidth();
+
+ private:
+  // Overridden from View.
   virtual gfx::Size GetPreferredSize();
+  virtual void Layout();
+  virtual void ViewHierarchyChanged(bool is_add, View* parent, View* child);
+  virtual std::string GetClassName() const;
 
-  // Overridden for keyboard UI purpose
+  // Overrideen from View for keyboard UI purpose.
   virtual bool OnKeyPressed(const KeyEvent& event);
   virtual bool OnMouseWheel(const MouseWheelEvent& e);
 
-  virtual void ViewHierarchyChanged(bool is_add, View *parent, View *child);
-
-  // Overridden from ScrollBar
+  // Overridden from ScrollBar.
   virtual void Update(int viewport_size, int content_size, int current_pos);
-  virtual int GetLayoutSize() const;
   virtual int GetPosition() const;
+  virtual int GetLayoutSize() const;
 
-  // Return the system sizes
-  static int GetHorizontalScrollBarHeight();
-  static int GetVerticalScrollBarWidth();
+  // init border
+  NativeScrollBarWrapper* native_wrapper_;
 
- private:
-#if defined(OS_WIN)
-  // The sb_view_ takes care of keeping sb_container in sync with the
-  // view hierarchy
-  NativeViewHost* sb_view_;
-#endif  // defined(OS_WIN)
-
-  // sb_container_ is a custom hwnd that we use to wrap the real
-  // windows scrollbar. We need to do this to get the scroll events
-  // without having to do anything special in the high level hwnd.
-  ScrollBarContainer* sb_container_;
+  DISALLOW_COPY_AND_ASSIGN(NativeScrollBar);
 };
 
 }  // namespace views
 
-#endif  // #ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLLBAR_H_
+#endif  // VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_H_
+
diff --git a/views/controls/scrollbar/native_scroll_bar_win.cc b/views/controls/scrollbar/native_scroll_bar_win.cc
new file mode 100644
index 0000000..b15be33
--- /dev/null
+++ b/views/controls/scrollbar/native_scroll_bar_win.cc
@@ -0,0 +1,346 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "views/controls/scrollbar/native_scroll_bar_win.h"
+
+#include <algorithm>
+#include <string>
+
+#include "base/message_loop.h"
+#include "base/window_impl.h"
+#include "views/controls/scrollbar/native_scroll_bar.h"
+#include "views/controls/scrollbar/scroll_bar.h"
+#include "views/widget/widget.h"
+
+namespace views {
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// ScrollBarContainer
+//
+// Since windows scrollbars only send notifications to their parent hwnd, we
+// use instances of this class to wrap native scrollbars.
+//
+/////////////////////////////////////////////////////////////////////////////
+class ScrollBarContainer : public base::WindowImpl {
+ public:
+  explicit ScrollBarContainer(ScrollBar* parent)
+      : parent_(parent),
+        scrollbar_(NULL) {
+    set_window_style(WS_CHILD);
+    Init(parent->GetWidget()->GetNativeView(), gfx::Rect());
+    ShowWindow(hwnd(), SW_SHOW);
+  }
+
+  virtual ~ScrollBarContainer() {
+  }
+
+  BEGIN_MSG_MAP_EX(ScrollBarContainer);
+    MSG_WM_CREATE(OnCreate);
+    MSG_WM_ERASEBKGND(OnEraseBkgnd);
+    MSG_WM_PAINT(OnPaint);
+    MSG_WM_SIZE(OnSize);
+    MSG_WM_HSCROLL(OnHorizScroll);
+    MSG_WM_VSCROLL(OnVertScroll);
+  END_MSG_MAP();
+
+  HWND GetScrollBarHWND() {
+    return scrollbar_;
+  }
+
+  // Invoked when the scrollwheel is used
+  void ScrollWithOffset(int o) {
+    SCROLLINFO si;
+    si.cbSize = sizeof(si);
+    si.fMask = SIF_POS;
+    GetScrollInfo(scrollbar_, SB_CTL, &si);
+    int pos = si.nPos - o;
+
+    if (pos < parent_->GetMinPosition())
+      pos = parent_->GetMinPosition();
+    else if (pos > parent_->GetMaxPosition())
+      pos = parent_->GetMaxPosition();
+
+    ScrollBarController* sbc = parent_->GetController();
+    sbc->ScrollToPosition(parent_, pos);
+
+    si.nPos = pos;
+    si.fMask = SIF_POS;
+    SetScrollInfo(scrollbar_, SB_CTL, &si, TRUE);
+  }
+
+ private:
+
+  LRESULT OnCreate(LPCREATESTRUCT create_struct) {
+    scrollbar_ = CreateWindow(L"SCROLLBAR", L"",
+                              WS_CHILD | (parent_->IsHorizontal() ?
+                                          SBS_HORZ : SBS_VERT),
+                              0, 0, parent_->width(), parent_->height(),
+                              hwnd(), NULL, NULL, NULL);
+    ShowWindow(scrollbar_, SW_SHOW);
+    return 1;
+  }
+
+  LRESULT OnEraseBkgnd(HDC dc) {
+    return 1;
+  }
+
+  void OnPaint(HDC ignore) {
+    PAINTSTRUCT ps;
+    HDC dc = BeginPaint(hwnd(), &ps);
+    EndPaint(hwnd(), &ps);
+  }
+
+  void OnSize(int type, const CSize& sz) {
+    SetWindowPos(scrollbar_,
+                 0, 0, 0, sz.cx, sz.cy,
+                 SWP_DEFERERASE | SWP_NOACTIVATE | SWP_NOCOPYBITS |
+                 SWP_NOOWNERZORDER | SWP_NOSENDCHANGING | SWP_NOZORDER);
+  }
+
+  void OnScroll(int code, HWND source, bool is_horizontal) {
+    int pos;
+
+    if (code == SB_ENDSCROLL) {
+      return;
+    }
+
+    // If we receive an event from the scrollbar, make the view
+    // component focused so we actually get mousewheel events.
+    if (source != NULL) {
+      Widget* widget = parent_->GetWidget();
+      if (widget && widget->GetNativeView() != GetFocus()) {
+        parent_->RequestFocus();
+      }
+    }
+
+    SCROLLINFO si;
+    si.cbSize = sizeof(si);
+    si.fMask = SIF_POS | SIF_TRACKPOS;
+    GetScrollInfo(scrollbar_, SB_CTL, &si);
+    pos = si.nPos;
+
+    ScrollBarController* sbc = parent_->GetController();
+
+    switch (code) {
+      case SB_BOTTOM:  // case SB_RIGHT:
+        pos = parent_->GetMaxPosition();
+        break;
+      case SB_TOP:  // case SB_LEFT:
+        pos = parent_->GetMinPosition();
+        break;
+      case SB_LINEDOWN:  //  case SB_LINERIGHT:
+        pos += sbc->GetScrollIncrement(parent_, false, true);
+        pos = std::min(parent_->GetMaxPosition(), pos);
+        break;
+      case SB_LINEUP:  //  case SB_LINELEFT:
+        pos -= sbc->GetScrollIncrement(parent_, false, false);
+        pos = std::max(parent_->GetMinPosition(), pos);
+        break;
+      case SB_PAGEDOWN:  //  case SB_PAGERIGHT:
+        pos += sbc->GetScrollIncrement(parent_, true, true);
+        pos = std::min(parent_->GetMaxPosition(), pos);
+        break;
+      case SB_PAGEUP:  // case SB_PAGELEFT:
+        pos -= sbc->GetScrollIncrement(parent_, true, false);
+        pos = std::max(parent_->GetMinPosition(), pos);
+        break;
+      case SB_THUMBPOSITION:
+      case SB_THUMBTRACK:
+        pos = si.nTrackPos;
+        if (pos < parent_->GetMinPosition())
+          pos = parent_->GetMinPosition();
+        else if (pos > parent_->GetMaxPosition())
+          pos = parent_->GetMaxPosition();
+        break;
+      default:
+        break;
+    }
+
+    sbc->ScrollToPosition(parent_, pos);
+
+    si.nPos = pos;
+    si.fMask = SIF_POS;
+    SetScrollInfo(scrollbar_, SB_CTL, &si, TRUE);
+
+    // Note: the system scrollbar modal loop doesn't give a chance
+    // to our message_loop so we need to call DidProcessMessage()
+    // manually.
+    //
+    // Sadly, we don't know what message has been processed. We may
+    // want to remove the message from DidProcessMessage()
+    MSG dummy;
+    dummy.hwnd = NULL;
+    dummy.message = 0;
+    MessageLoopForUI::current()->DidProcessMessage(dummy);
+  }
+
+  // note: always ignore 2nd param as it is 16 bits
+  void OnHorizScroll(int n_sb_code, int ignore, HWND source) {
+    OnScroll(n_sb_code, source, true);
+  }
+
+  // note: always ignore 2nd param as it is 16 bits
+  void OnVertScroll(int n_sb_code, int ignore, HWND source) {
+    OnScroll(n_sb_code, source, false);
+  }
+
+  ScrollBar* parent_;
+  HWND scrollbar_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScrollBarContainer);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBarWin, public:
+
+NativeScrollBarWin::NativeScrollBarWin(NativeScrollBar* scroll_bar)
+    : native_scroll_bar_(scroll_bar),
+      sb_container_(NULL) {
+  set_focus_view(scroll_bar);
+}
+
+NativeScrollBarWin::~NativeScrollBarWin() {
+  if (sb_container_) {
+    // We always destroy the scrollbar container explicitly to cover all
+    // cases including when the container is no longer connected to a
+    // widget tree.
+    DestroyWindow(sb_container_->hwnd());
+    delete sb_container_;
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBarWin, View overrides:
+
+void NativeScrollBarWin::Layout() {
+  SetBounds(native_scroll_bar_->GetLocalBounds(true));
+  NativeControlWin::Layout();
+}
+
+gfx::Size NativeScrollBarWin::GetPreferredSize() {
+  if (native_scroll_bar_->IsHorizontal())
+    return gfx::Size(0, GetHorizontalScrollBarHeight());
+  return gfx::Size(GetVerticalScrollBarWidth(), 0);
+}
+
+bool NativeScrollBarWin::OnKeyPressed(const KeyEvent& event) {
+  if (!sb_container_)
+    return false;
+  int code = -1;
+  switch (event.GetCharacter()) {
+    case VK_UP:
+      if (!native_scroll_bar_->IsHorizontal())
+        code = SB_LINEUP;
+      break;
+    case VK_PRIOR:
+      code = SB_PAGEUP;
+      break;
+    case VK_NEXT:
+      code = SB_PAGEDOWN;
+      break;
+    case VK_DOWN:
+      if (!native_scroll_bar_->IsHorizontal())
+        code = SB_LINEDOWN;
+      break;
+    case VK_HOME:
+      code = SB_TOP;
+      break;
+    case VK_END:
+      code = SB_BOTTOM;
+      break;
+    case VK_LEFT:
+      if (native_scroll_bar_->IsHorizontal())
+        code = SB_LINELEFT;
+      break;
+    case VK_RIGHT:
+      if (native_scroll_bar_->IsHorizontal())
+        code = SB_LINERIGHT;
+      break;
+  }
+  if (code != -1) {
+    SendMessage(sb_container_->hwnd(),
+                native_scroll_bar_->IsHorizontal() ? WM_HSCROLL : WM_VSCROLL,
+                MAKELONG(static_cast<WORD>(code), 0), 0L);
+    return true;
+  }
+  return false;
+}
+
+bool NativeScrollBarWin::OnMouseWheel(const MouseWheelEvent& e) {
+  if (!sb_container_)
+    return false;
+  sb_container_->ScrollWithOffset(e.GetOffset());
+  return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBarWin, NativeControlWin overrides:
+
+void NativeScrollBarWin::CreateNativeControl() {
+  sb_container_ = new ScrollBarContainer(native_scroll_bar_);
+  NativeControlCreated(sb_container_->hwnd());
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// NativeScrollBarWin, NativeScrollBarWrapper overrides:
+
+int NativeScrollBarWin::GetPosition() const {
+  SCROLLINFO si;
+  si.cbSize = sizeof(si);
+  si.fMask = SIF_POS;
+  GetScrollInfo(sb_container_->GetScrollBarHWND(), SB_CTL, &si);
+  return si.nPos;
+}
+
+View* NativeScrollBarWin::GetView() {
+  return this;
+}
+
+void NativeScrollBarWin::Update(int viewport_size,
+                                int content_size,
+                                int current_pos) {
+  if (!sb_container_)
+    return;
+
+  if (content_size < 0)
+    content_size = 0;
+
+  if (current_pos < 0)
+    current_pos = 0;
+
+  if (current_pos > content_size)
+    current_pos = content_size;
+
+  SCROLLINFO si;
+  si.cbSize = sizeof(si);
+  si.fMask = SIF_DISABLENOSCROLL | SIF_POS | SIF_RANGE | SIF_PAGE;
+  si.nMin = 0;
+  si.nMax = content_size;
+  si.nPos = current_pos;
+  si.nPage = viewport_size;
+  SetScrollInfo(sb_container_->GetScrollBarHWND(), SB_CTL, &si, TRUE);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// NativewScrollBarWrapper, public:
+
+// static
+NativeScrollBarWrapper* NativeScrollBarWrapper::CreateWrapper(
+    NativeScrollBar* scroll_bar) {
+  return new NativeScrollBarWin(scroll_bar);
+}
+
+// static
+int NativeScrollBarWrapper::GetHorizontalScrollBarHeight() {
+  return GetSystemMetrics(SM_CYHSCROLL);
+}
+
+// static
+int NativeScrollBarWrapper::GetVerticalScrollBarWidth() {
+  return GetSystemMetrics(SM_CXVSCROLL);
+}
+
+}  // namespace views
+
diff --git a/views/controls/scrollbar/native_scroll_bar_win.h b/views/controls/scrollbar/native_scroll_bar_win.h
new file mode 100644
index 0000000..566f036
--- /dev/null
+++ b/views/controls/scrollbar/native_scroll_bar_win.h
@@ -0,0 +1,62 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_WIN_H_
+#define VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_WIN_H_
+
+#include "views/controls/native_control_win.h"
+#include "views/controls/scrollbar/native_scroll_bar_wrapper.h"
+
+namespace views {
+
+class ScrollBarContainer;
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// NativeScrollBarWin
+//
+// A View subclass that wraps a Native Windows scrollbar control.
+//
+// A scrollbar is either horizontal or vertical.
+//
+/////////////////////////////////////////////////////////////////////////////
+class NativeScrollBarWin : public NativeControlWin,
+                           public NativeScrollBarWrapper {
+ public:
+  // Create new scrollbar, either horizontal or vertical.
+  explicit NativeScrollBarWin(NativeScrollBar* native_scroll_bar);
+  virtual ~NativeScrollBarWin();
+
+ private:
+  // Overridden from View for layout purpose.
+  virtual void Layout();
+  virtual gfx::Size GetPreferredSize();
+
+  // Overridden from View for keyboard UI purpose.
+  virtual bool OnKeyPressed(const KeyEvent& event);
+  virtual bool OnMouseWheel(const MouseWheelEvent& e);
+
+  // Overridden from NativeControlWin.
+  virtual void CreateNativeControl();
+
+  // Overridden from ScrollBarWrapper.
+  virtual int GetPosition() const;
+  virtual View* GetView();
+  virtual void Update(int viewport_size, int content_size, int current_pos);
+
+  // The NativeScrollBar we are bound to.
+  NativeScrollBar* native_scroll_bar_;
+
+  // sb_container_ is a custom hwnd that we use to wrap the real
+  // windows scrollbar. We need to do this to get the scroll events
+  // without having to do anything special in the high level hwnd.
+  ScrollBarContainer* sb_container_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeScrollBarWin);
+};
+
+}  // namespace views
+
+#endif  // #ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_WIN_H_
+
diff --git a/views/controls/scrollbar/native_scroll_bar_wrapper.h b/views/controls/scrollbar/native_scroll_bar_wrapper.h
new file mode 100644
index 0000000..6fb68ea
--- /dev/null
+++ b/views/controls/scrollbar/native_scroll_bar_wrapper.h
@@ -0,0 +1,42 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved. Use of this
+// source code is governed by a BSD-style license that can be found in the
+// LICENSE file.
+
+#ifndef VIEWS_CONTROLS_NATIVE_SCROLL_BAR_WRAPPER_H_
+#define VIEWS_CONTROLS_NATIVE_SCROLL_BAR_WRAPPER_H_
+
+namespace views {
+
+class NativeScrollBar;
+class View;
+
+// A specialization of NativeControlWrapper that hosts a platform-native
+// scroll bar.
+class NativeScrollBarWrapper {
+ public:
+  virtual ~NativeScrollBarWrapper() {}
+
+  // Updates the scroll bar appearance given a viewport size, content size and
+  // current position.
+  virtual void Update(int viewport_size,
+                      int content_size,
+                      int current_pos) = 0;
+
+  // Retrieves the views::View that hosts the native control.
+  virtual View* GetView() = 0;
+
+  // Returns the position of the scrollbar.
+  virtual int GetPosition() const = 0;
+
+  // Creates an appropriate NativeScrollBarWrapper for the platform.
+  static NativeScrollBarWrapper* CreateWrapper(NativeScrollBar* button);
+
+  // Returns the system sizes of vertical/horizontal scroll bars.
+  static int GetVerticalScrollBarWidth();
+  static int GetHorizontalScrollBarHeight();
+};
+
+}  // namespace views
+
+#endif  // VIEWS_CONTROLS_NATIVE_SCROLL_BAR_WRAPPER_H_
+
diff --git a/views/controls/scrollbar/scroll_bar.h b/views/controls/scrollbar/scroll_bar.h
index 36a9d2e..9354fcb 100644
--- a/views/controls/scrollbar/scroll_bar.h
+++ b/views/controls/scrollbar/scroll_bar.h
@@ -5,8 +5,8 @@
 #ifndef VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
 #define VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
 
-#include "views/view.h"
 #include "views/event.h"
+#include "views/view.h"
 
 namespace views {
 
@@ -100,3 +100,4 @@ class ScrollBar : public View {
 }  // namespace views
 
 #endif  // #ifndef VIEWS_CONTROLS_SCROLLBAR_SCROLLBAR_H_
+
diff --git a/views/views.gyp b/views/views.gyp
index e9456e6..e1277cb 100644
--- a/views/views.gyp
+++ b/views/views.gyp
@@ -159,6 +159,9 @@
         'controls/scroll_view.h',
         'controls/scrollbar/bitmap_scroll_bar.cc',
         'controls/scrollbar/bitmap_scroll_bar.h',
+        'controls/scrollbar/native_scroll_bar_wrapper.h',
+        'controls/scrollbar/native_scroll_bar_win.cc',
+        'controls/scrollbar/native_scroll_bar_win.h',
         'controls/scrollbar/native_scroll_bar.cc',
         'controls/scrollbar/native_scroll_bar.h',
         'controls/scrollbar/scroll_bar.cc',