diff --git a/BUILD.gn b/BUILD.gn
index f91ea0e..c43b074 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -929,6 +929,7 @@
     "fpdfsdk/pdfwindow/PWL_Utils.h",
     "fpdfsdk/pdfwindow/PWL_Wnd.cpp",
     "fpdfsdk/pdfwindow/PWL_Wnd.h",
+    "fpdfsdk/pdfwindow/cpwl_color.h",
   ]
   configs += [ ":pdfium_core_config" ]
   deps = [
diff --git a/core/fxcrt/cfx_observable.h b/core/fxcrt/cfx_observable.h
index dc869b1..856ccc2 100644
--- a/core/fxcrt/cfx_observable.h
+++ b/core/fxcrt/cfx_observable.h
@@ -20,7 +20,7 @@
       if (m_pObservedPtr)
         m_pObservedPtr->AddObservedPtr(this);
     }
-    ObservedPtr(const ObservedPtr& that) = delete;
+    ObservedPtr(const ObservedPtr& that) : ObservedPtr(that.Get()) {}
     ~ObservedPtr() {
       if (m_pObservedPtr)
         m_pObservedPtr->RemoveObservedPtr(this);
@@ -36,7 +36,10 @@
       ASSERT(m_pObservedPtr);
       m_pObservedPtr = nullptr;
     }
-    ObservedPtr& operator=(const ObservedPtr& that) = delete;
+    ObservedPtr& operator=(const ObservedPtr& that) {
+      Reset(that.Get());
+      return *this;
+    }
     bool operator==(const ObservedPtr& that) const {
       return m_pObservedPtr == that.m_pObservedPtr;
     }
diff --git a/fpdfsdk/cpdfsdk_widget.h b/fpdfsdk/cpdfsdk_widget.h
index b630738..69114d1 100644
--- a/fpdfsdk/cpdfsdk_widget.h
+++ b/fpdfsdk/cpdfsdk_widget.h
@@ -16,7 +16,7 @@
 #include "core/fxcrt/fx_string.h"
 #include "fpdfsdk/cpdfsdk_baannot.h"
 #include "fpdfsdk/pdfsdk_fieldaction.h"
-#include "fpdfsdk/pdfwindow/PWL_Wnd.h"
+#include "fpdfsdk/pdfwindow/cpwl_color.h"
 
 class CFX_RenderDevice;
 class CPDF_Annot;
diff --git a/fpdfsdk/formfiller/cffl_formfiller.cpp b/fpdfsdk/formfiller/cffl_formfiller.cpp
index 7c1dec4..281057a 100644
--- a/fpdfsdk/formfiller/cffl_formfiller.cpp
+++ b/fpdfsdk/formfiller/cffl_formfiller.cpp
@@ -289,7 +289,7 @@
 
   PWL_CREATEPARAM cp;
   cp.pParentWnd = nullptr;
-  cp.pProvider = this;
+  cp.pProvider.Reset(this);
   cp.rcRectWnd = GetPDFWindowRect();
 
   uint32_t dwCreateFlags = PWS_BORDER | PWS_BACKGROUND | PWS_VISIBLE;
@@ -359,7 +359,7 @@
     }
   } else {
     PWL_CREATEPARAM cp = GetCreateParam();
-    cp.pAttachedWidget = m_pWidget;
+    cp.pAttachedWidget.Reset(m_pWidget);
 
     CFFL_PrivateData* pPrivateData = new CFFL_PrivateData;
     pPrivateData->pWidget = m_pWidget;
diff --git a/fpdfsdk/pdfwindow/PWL_Wnd.cpp b/fpdfsdk/pdfwindow/PWL_Wnd.cpp
index 78a4363..d2e7437 100644
--- a/fpdfsdk/pdfwindow/PWL_Wnd.cpp
+++ b/fpdfsdk/pdfwindow/PWL_Wnd.cpp
@@ -264,8 +264,8 @@
 }
 
 void CPWL_Wnd::InvalidateProvider(IPWL_Provider* provider) {
-  if (m_sPrivateParam.pProvider == provider)
-    m_sPrivateParam.pProvider = nullptr;
+  if (m_sPrivateParam.pProvider.Get() == provider)
+    m_sPrivateParam.pProvider.Reset();
 }
 
 void CPWL_Wnd::Destroy() {
@@ -289,7 +289,7 @@
 
   DestroyMsgControl();
 
-  FXSYS_memset(&m_sPrivateParam, 0, sizeof(PWL_CREATEPARAM));
+  m_sPrivateParam.Reset();
   m_aChildren.RemoveAll();
   m_pVScrollBar = nullptr;
 }
@@ -420,8 +420,10 @@
     rcWin.bottom += PWL_INVALIDATE_INFLATE;
 
     if (CFX_SystemHandler* pSH = GetSystemHandler()) {
-      if (CPDFSDK_Widget* widget = m_sPrivateParam.pAttachedWidget)
+      if (CPDFSDK_Widget* widget = static_cast<CPDFSDK_Widget*>(
+              m_sPrivateParam.pAttachedWidget.Get())) {
         pSH->InvalidateRect(widget, rcWin);
+      }
     }
   }
 }
@@ -832,7 +834,7 @@
 }
 
 IPWL_Provider* CPWL_Wnd::GetProvider() const {
-  return m_sPrivateParam.pProvider;
+  return m_sPrivateParam.pProvider.Get();
 }
 
 IPVT_FontMap* CPWL_Wnd::GetFontMap() const {
@@ -880,9 +882,7 @@
 
   if (IPWL_Provider* pProvider = GetProvider()) {
     mt.Concat(pProvider->GetWindowMatrix(GetAttachedData()));
-    return mt;
   }
-
   return mt;
 }
 
diff --git a/fpdfsdk/pdfwindow/PWL_Wnd.h b/fpdfsdk/pdfwindow/PWL_Wnd.h
index bba14f2..204fe32 100644
--- a/fpdfsdk/pdfwindow/PWL_Wnd.h
+++ b/fpdfsdk/pdfwindow/PWL_Wnd.h
@@ -11,10 +11,12 @@
 #include <vector>
 
 #include "core/fpdfdoc/cpdf_formcontrol.h"
+#include "core/fxcrt/cfx_observable.h"
 #include "core/fxcrt/fx_basic.h"
 #include "fpdfsdk/cfx_systemhandler.h"
+#include "fpdfsdk/cpdfsdk_widget.h"
+#include "fpdfsdk/pdfwindow/cpwl_color.h"
 
-class CPDFSDK_Widget;
 class CPWL_MsgControl;
 class CPWL_ScrollBar;
 class CPWL_Timer;
@@ -91,42 +93,17 @@
   CPWL_Dash(int32_t dash, int32_t gap, int32_t phase)
       : nDash(dash), nGap(gap), nPhase(phase) {}
 
+  void Reset() {
+    nDash = 0;
+    nGap = 0;
+    nPhase = 0;
+  }
+
   int32_t nDash;
   int32_t nGap;
   int32_t nPhase;
 };
 
-struct CPWL_Color {
-  CPWL_Color(int32_t type = COLORTYPE_TRANSPARENT,
-             FX_FLOAT color1 = 0.0f,
-             FX_FLOAT color2 = 0.0f,
-             FX_FLOAT color3 = 0.0f,
-             FX_FLOAT color4 = 0.0f)
-      : nColorType(type),
-        fColor1(color1),
-        fColor2(color2),
-        fColor3(color3),
-        fColor4(color4) {}
-
-  CPWL_Color(int32_t r, int32_t g, int32_t b)
-      : nColorType(COLORTYPE_RGB),
-        fColor1(r / 255.0f),
-        fColor2(g / 255.0f),
-        fColor3(b / 255.0f),
-        fColor4(0) {}
-
-  void ConvertColorType(int32_t other_nColorType);
-
-  /*
-  COLORTYPE_TRANSPARENT
-  COLORTYPE_RGB
-  COLORTYPE_CMYK
-  COLORTYPE_GRAY
-  */
-  int32_t nColorType;
-  FX_FLOAT fColor1, fColor2, fColor3, fColor4;
-};
-
 inline bool operator==(const CPWL_Color& c1, const CPWL_Color& c2) {
   return c1.nColorType == c2.nColorType && c1.fColor1 - c2.fColor1 < 0.0001 &&
          c1.fColor1 - c2.fColor1 > -0.0001 &&
@@ -161,7 +138,7 @@
 #define PWL_CBBUTTON_TRIANGLE_HALFLEN 3.0f
 #define PWL_INVALIDATE_INFLATE 2
 
-class IPWL_Provider {
+class IPWL_Provider : public CFX_Observable<IPWL_Provider> {
  public:
   virtual ~IPWL_Provider() {}
 
@@ -191,14 +168,38 @@
   PWL_CREATEPARAM();
   PWL_CREATEPARAM(const PWL_CREATEPARAM& other);
 
+  void Reset() {
+    rcRectWnd.Reset();
+    pSystemHandler = nullptr;
+    pFontMap = nullptr;
+    pProvider.Reset();
+    pFocusHandler = nullptr;
+    dwFlags = 0;
+    sBackgroundColor.Reset();
+    pAttachedWidget.Reset();
+    nBorderStyle = BorderStyle::SOLID;
+    dwBorderWidth = 0;
+    sBorderColor.Reset();
+    sTextColor.Reset();
+    sTextStrokeColor.Reset();
+    nTransparency = 0;
+    fFontSize = 0.0f;
+    sDash.Reset();
+    pAttachedData = nullptr;
+    pParentWnd = nullptr;
+    pMsgControl = nullptr;
+    eCursorType = 0;
+    mtChild.SetIdentity();
+  }
+
   CFX_FloatRect rcRectWnd;            // required
   CFX_SystemHandler* pSystemHandler;  // required
-  IPVT_FontMap* pFontMap;             // required for text window
-  IPWL_Provider* pProvider;           // required for self coordinate
+  IPVT_FontMap* pFontMap;             // required
+  IPWL_Provider::ObservedPtr pProvider;  // required
   IPWL_FocusHandler* pFocusHandler;   // optional
   uint32_t dwFlags;                   // optional
   CPWL_Color sBackgroundColor;        // optional
-  CPDFSDK_Widget* pAttachedWidget;    // required for no-reader framework
+  CPDFSDK_Widget::ObservedPtr pAttachedWidget;  // required
   BorderStyle nBorderStyle;           // optional
   int32_t dwBorderWidth;              // optional
   CPWL_Color sBorderColor;            // optional
diff --git a/fpdfsdk/pdfwindow/cpwl_color.h b/fpdfsdk/pdfwindow/cpwl_color.h
new file mode 100644
index 0000000..c1f9e6e
--- /dev/null
+++ b/fpdfsdk/pdfwindow/cpwl_color.h
@@ -0,0 +1,48 @@
+// Copyright 2017 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#ifndef FPDFSDK_PDFWINDOW_CPWL_COLOR_H_
+#define FPDFSDK_PDFWINDOW_CPWL_COLOR_H_
+
+#include "core/fpdfdoc/cpdf_formcontrol.h"
+
+struct CPWL_Color {
+  CPWL_Color(int32_t type = COLORTYPE_TRANSPARENT,
+             FX_FLOAT color1 = 0.0f,
+             FX_FLOAT color2 = 0.0f,
+             FX_FLOAT color3 = 0.0f,
+             FX_FLOAT color4 = 0.0f)
+      : nColorType(type),
+        fColor1(color1),
+        fColor2(color2),
+        fColor3(color3),
+        fColor4(color4) {}
+
+  CPWL_Color(int32_t r, int32_t g, int32_t b)
+      : nColorType(COLORTYPE_RGB),
+        fColor1(r / 255.0f),
+        fColor2(g / 255.0f),
+        fColor3(b / 255.0f),
+        fColor4(0) {}
+
+  void ConvertColorType(int32_t other_nColorType);
+
+  void Reset() {
+    nColorType = COLORTYPE_TRANSPARENT;
+    fColor1 = 0.0f;
+    fColor2 = 0.0f;
+    fColor3 = 0.0f;
+    fColor4 = 0.0f;
+  }
+
+  int32_t nColorType;
+  FX_FLOAT fColor1;
+  FX_FLOAT fColor2;
+  FX_FLOAT fColor3;
+  FX_FLOAT fColor4;
+};
+
+#endif  // FPDFSDK_PDFWINDOW_CPWL_COLOR_H_