gpu: Bind dummy GL API when no context is current

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 f925f64ffa88af185c41ca880c09a484e094706d..42a937062ed4850eb3f09256d1c64076077da83b 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -22,6 +22,9 @@ namespace gfx {
 static GLApi* g_gl;
 // A GL Api that calls directly into the driver.
 static RealGLApi* g_real_gl;
+// A GL Api that does nothing but warn about illegal GL calls without a context
+// current.
+static NoContextGLApi* g_no_context_gl;
 // A GL Api that calls TRACE and then calls another GL api.
 static TraceGLApi* g_trace_gl;
 // GL version used when initializing dynamic bindings.
@@ -258,6 +261,7 @@ void InitializeStaticGLBindingsGL() {
   if (!g_real_gl) {
     g_real_gl = new RealGLApi();
     g_trace_gl = new TraceGLApi(g_real_gl);
+    g_no_context_gl = new NoContextGLApi();
   }
   g_real_gl->Initialize(&g_driver_gl);
   g_gl = g_real_gl;
@@ -280,6 +284,10 @@ void SetGLToRealGLApi() {
   SetGLApi(g_gl);
 }
 
+void SetGLApiToNoContext() {
+  SetGLApi(g_no_context_gl);
+}
+
 void InitializeDynamicGLBindingsGL(GLContext* context) {
   g_driver_gl.InitializeCustomDynamicBindings(context);
   DCHECK(context && context->IsCurrent(NULL) && !g_version_info);
@@ -356,6 +364,12 @@ void RealGLApi::Initialize(DriverGL* driver) {
 TraceGLApi::~TraceGLApi() {
 }
 
+NoContextGLApi::NoContextGLApi() {
+}
+
+NoContextGLApi::~NoContextGLApi() {
+}
+
 VirtualGLApi::VirtualGLApi()
     : real_context_(NULL),
       current_context_(NULL) {