Add kApplicationIdKey for ShellSurface::GetApplicationId and SetApplicationId

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 e4fff6f17a71d2ddb9ce98a97105c2dec3b6f52f..9433dedbf4d1602f18a5582f25bc50614e741a1b 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -555,14 +555,13 @@ void ShellSurface::UpdateSystemModal() {
 void ShellSurface::SetApplicationId(aura::Window* window,
                                     const std::string& id) {
   TRACE_EVENT1("exo", "ShellSurface::SetApplicationId", "application_id", id);
-  const ash::ShelfID shelf_id(id);
-  window->SetProperty(ash::kShelfIDKey, new std::string(shelf_id.Serialize()));
+  window->SetProperty(aura::client::kAppIdKey, new std::string(id));

[msw, 2017/05/16 17:00:06]

As this is the only place using kAppIdKey, it should probably be defined
locally, in this file, not in aura::client.

[msw, 2017/05/16 17:03:27]

And perhaps renaming the property to disambiguate it from other app ids would be
helpful. Maybe kShellSurfaceIdKey or kExoIdKey?

[yawano, 2017/05/17 08:36:49]

Done. Renamed to kExoAppIdKey as oshima has suggested, and move the property to
this file.

 }
 
 // static
 const std::string ShellSurface::GetApplicationId(aura::Window* window) {
-  return ash::ShelfID::Deserialize(window->GetProperty(ash::kShelfIDKey))
-      .app_id;
+  std::string* string_ptr = window->GetProperty(aura::client::kAppIdKey);
+  return string_ptr ? *string_ptr : std::string();
 }
 
 void ShellSurface::SetApplicationId(const std::string& application_id) {