Handle app custom icon via aura::Window property.

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index 998769b20df6aeb73b117963a2e0d1d153fef79a..70c62cd2948bbae0bc1c96daca571ae313b96ba8 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -531,6 +531,11 @@ void ShellSurface::SetApplicationId(const std::string& application_id) {
     SetApplicationId(widget_->GetNativeWindow(), application_id);
 }
 
+void ShellSurface::SetAppIcon(const gfx::ImageSkia& icon) {
+  icon_ = icon;
+  widget_->UpdateWindowIcon();

[reveman, 2017/06/01 22:05:36]

nit: please leave this up to the caller so icon can be set before we have a
widget and unnecessary updates can be avoided

[khmel, 2017/06/01 22:19:27]

I did it the same way as SetTitle

  if (widget_)
    widget_->UpdateWindowIcon();

[reveman, 2017/06/01 22:26:00]

Sounds good. Thanks!

+}
+
 void ShellSurface::Move() {
   TRACE_EVENT0("exo", "ShellSurface::Move");
 
@@ -819,6 +824,10 @@ base::string16 ShellSurface::GetWindowTitle() const {
   return title_;
 }
 
+gfx::ImageSkia ShellSurface::GetWindowIcon() {
+  return icon_;
+}
+
 void ShellSurface::SaveWindowPlacement(const gfx::Rect& bounds,
                                        ui::WindowShowState show_state) {
   if (bounds_mode_ != BoundsMode::CLIENT)