Update from chromium https://crrev.com/302282

ui/gl/gl_gl_api_implementation.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 "ui/gl/gl_gl_api_implementation.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 424 matching lines @@
         return false;
       }
     }
   }
 
   DCHECK_EQ(real_context_, GLContext::GetRealCurrent());
   DCHECK(real_context_->IsCurrent(NULL));
   DCHECK(virtual_context->IsCurrent(surface));
 
   if (switched_contexts || virtual_context != current_context_) {
-    // There should be no errors from the previous context leaking into the
-    // new context.
-    DCHECK_EQ(glGetErrorFn(), static_cast<GLenum>(GL_NO_ERROR));
+#if DCHECK_IS_ON
+    GLenum error = glGetErrorFn();
+    // Accepting a context loss error here enables using debug mode to work on
+    // context loss handling in virtual context mode.
+    // There should be no other errors from the previous context leaking into
+    // the new context.
+    DCHECK(error == GL_NO_ERROR || error == GL_CONTEXT_LOST_KHR);
+#endif
 
     // Set all state that is different from the real state
     GLApi* temp = GetCurrentGLApi();
     SetGLToRealGLApi();
     if (virtual_context->GetGLStateRestorer()->IsInitialized()) {
       virtual_context->GetGLStateRestorer()->RestoreState(
           (current_context_ && !switched_contexts)
               ? current_context_->GetGLStateRestorer()
               : NULL);
     }
@@ skipping 37 matching lines @@
 ScopedSetGLToRealGLApi::ScopedSetGLToRealGLApi()
     : old_gl_api_(GetCurrentGLApi()) {
   SetGLToRealGLApi();
 }
 
 ScopedSetGLToRealGLApi::~ScopedSetGLToRealGLApi() {
   SetGLApi(old_gl_api_);
 }
 
 }  // namespace gfx