Improve context loss error handling

ui/gl/gl_gl_api_implementation.cc

Index: ui/gl/gl_gl_api_implementation.cc
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index f4dca224e2f884b91ddaed513c6f02542e951839..56d3ff21cdd48495dcc13f30ddb66f0b80dc54ac 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -442,9 +442,14 @@ bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
   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 !defined(NDEBUG)

[Ken Russell (switch to Gerrit), 2014/10/29 22:21:21]

Please use #if DCHECK_IS_ON instead. Our Release mode bots use
dcheck_always_on=1.

[oetuaho-nv, 2014/10/30 09:17:14]

Got it, will do.

+    GLenum err = 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(err == GL_NO_ERROR || err == GL_CONTEXT_LOST_KHR);
+#endif
 
     // Set all state that is different from the real state
     GLApi* temp = GetCurrentGLApi();