Adding ThreadChecker validation to d'tors for client classes

remoting/client/display/fake_canvas.cc

 // Copyright 2016 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 "remoting/client/display/fake_canvas.h"
 
 namespace remoting {
 
 FakeCanvas::FakeCanvas() : weak_factory_(this) {}
 
-FakeCanvas::~FakeCanvas() {}
+FakeCanvas::~FakeCanvas() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
 
 void FakeCanvas::Clear() {}
 
 void FakeCanvas::SetTransformationMatrix(const std::array<float, 9>& matrix) {}
 
 void FakeCanvas::SetViewSize(int width, int height) {}
 
 void FakeCanvas::DrawTexture(int texture_id,
                              int texture_handle,
                              int vertex_buffer,
                              float alpha_multiplier) {}
 
 int FakeCanvas::GetVersion() const {
   return 0;
 }
 
 int FakeCanvas::GetMaxTextureSize() const {
   return 0;
 }
 
 base::WeakPtr<Canvas> FakeCanvas::GetWeakPtr() {
   DCHECK(thread_checker_.CalledOnValidThread());
   return weak_factory_.GetWeakPtr();
 }
 
 }  // namespace remoting