Fix icon on Windows XP taskbar

ui/gfx/win/window_impl.cc

Index: ui/gfx/win/window_impl.cc
diff --git a/ui/gfx/win/window_impl.cc b/ui/gfx/win/window_impl.cc
index b0c4fa7ad34349c7e10bb7a5663d13287ee65cec..c9f235f05f894c03e27793396b58cdd579591b4d 100644
--- a/ui/gfx/win/window_impl.cc
+++ b/ui/gfx/win/window_impl.cc
@@ -33,10 +33,12 @@ const wchar_t* const WindowImpl::kBaseClassName = L"Chrome_WidgetWin_";
 struct ClassInfo {
   UINT style;
   HICON icon;
+  HICON small_icon;
 
-  ClassInfo(int style, HICON icon)
+  ClassInfo(int style, HICON icon, HICON small_icon)
       : style(style),
-        icon(icon) {}
+        icon(icon),
+        small_icon(small_icon) {}
 
   // Compares two ClassInfos. Returns true if all members match.
   bool Equals(const ClassInfo& other) const {
@@ -135,7 +137,7 @@ ATOM ClassRegistrar::RetrieveClassAtom(const ClassInfo& class_info) {
       reinterpret_cast<HBRUSH>(GetStockObject(BLACK_BRUSH)),
       NULL,
       class_info.icon,
-      class_info.icon,
+      class_info.small_icon,
       &window_class);
   HMODULE instance = window_class.hInstance;
   ATOM atom = RegisterClassEx(&window_class);
@@ -256,7 +258,11 @@ void WindowImpl::Init(HWND parent, const Rect& bounds) {
 }
 
 HICON WindowImpl::GetDefaultWindowIcon() const {
-  return NULL;
+  return nullptr;
+}
+
+HICON WindowImpl::GetSmallWindowIcon() const {
+  return nullptr;
 }
 
 LRESULT WindowImpl::OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) {
@@ -305,7 +311,8 @@ LRESULT CALLBACK WindowImpl::WndProc(HWND hwnd,
 
 ATOM WindowImpl::GetWindowClassAtom() {
   HICON icon = GetDefaultWindowIcon();
-  ClassInfo class_info(initial_class_style(), icon);
+  HICON small_icon = GetSmallWindowIcon();
+  ClassInfo class_info(initial_class_style(), icon, small_icon);
   return ClassRegistrar::GetInstance()->RetrieveClassAtom(class_info);
 }