Remove unused |context| from GetDefaultParent().

ui/aura/demo/demo_main.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #include "base/macros.h"
@@ skipping 89 matching lines @@
  public:
   explicit DemoWindowParentingClient(aura::Window* window) : window_(window) {
     aura::client::SetWindowParentingClient(window_, this);
   }
 
   ~DemoWindowParentingClient() override {
     aura::client::SetWindowParentingClient(window_, nullptr);
   }
 
   // Overridden from aura::client::WindowParentingClient:
-  aura::Window* GetDefaultParent(aura::Window* context,
-                                 aura::Window* window,
+  aura::Window* GetDefaultParent(aura::Window* window,
                                  const gfx::Rect& bounds) override {
     if (!capture_client_) {
       capture_client_.reset(
           new aura::client::DefaultCaptureClient(window_->GetRootWindow()));
     }
     return window_;
   }
 
  private:
   aura::Window* window_;
@@ skipping 82 matching lines @@
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
 
   // The exit manager is in charge of calling the dtors of singleton objects.
   base::AtExitManager exit_manager;
 
   base::i18n::InitializeICU();
 
   return DemoMain();
 }