[Chromoting] Unit Tests for GlRenderer

remoting/client/gl_renderer.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/gl_renderer.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "remoting/client/gl_canvas.h"
@@ skipping 112 matching lines @@
   render_scheduled_ = true;
 }
 
 void GlRenderer::OnRender() {
   DCHECK(thread_checker_.CalledOnValidThread());
   render_scheduled_ = false;
   if (!delegate_ || !delegate_->CanRenderFrame()) {
     return;
   }
 
-  glClear(GL_COLOR_BUFFER_BIT);
-  desktop_.Draw();
-  cursor_.Draw();
-  if (cursor_feedback_.Draw()) {
-    RequestRender();
+  if (canvas_) {
+    glClear(GL_COLOR_BUFFER_BIT);
+    desktop_.Draw();
+    cursor_.Draw();
+    if (cursor_feedback_.Draw()) {
+      RequestRender();
+    }
   }
 
   delegate_->OnFrameRendered();
 
   while (!pending_done_callbacks_.empty()) {
     pending_done_callbacks_.front().Run();
     pending_done_callbacks_.pop();
   }
 }
 
 }  // namespace remoting