Remove the const for Window method in InstanceUpdate.

InstanceUpdate's Window method is used to get the pointer of window
in OnInstanceUpdate callback. If const, it prevents the operation on
the window, e.g window->SetProperty in ui, so remove the const.

BUG=1011235

Change-Id: I14deed57307a6dd465f0c0f3cae30c86cce6279e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1921008Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716067}

chrome/services/app_service/public/cpp/instance_update.cc

@@ -86,7 +86,7 @@ const std::string& InstanceUpdate::AppId() const {
   return delta_ ? delta_->AppId() : state_->AppId();
 }
 
-const aura::Window* InstanceUpdate::Window() const {
+aura::Window* InstanceUpdate::Window() const {
   return delta_ ? delta_->Window() : state_->Window();
 }
 

chrome/services/app_service/public/cpp/instance_update.h

@@ -59,7 +59,7 @@ class InstanceUpdate {
 
   const std::string& AppId() const;
 
-  const aura::Window* Window() const;
+  aura::Window* Window() const;
 
   const std::string& LaunchId() const;
   bool LaunchIdChanged() const;