gpu: Bind dummy GL API when no context is current

ui/gl/gl_gl_api_implementation.h

 // 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.
 
 #ifndef UI_GL_GL_GL_API_IMPLEMENTATION_H_
 #define UI_GL_GL_GL_API_IMPLEMENTATION_H_
 
 #include "base/compiler_specific.h"
 #include "ui/gl/gl_bindings.h"
-#include "ui/gl/gl_export.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Decoder;
 }
 }
 namespace gfx {
 
 class GLContext;
 class GLSurface;
 
 void InitializeStaticGLBindingsGL();
 void InitializeDynamicGLBindingsGL(GLContext* context);
 void InitializeDebugGLBindingsGL();
 void InitializeNullDrawGLBindingsGL();
 // TODO(danakj): Remove this when all test suites are using null-draw.
 bool HasInitializedNullDrawGLBindingsGL();
 bool SetNullDrawGLBindingsEnabledGL(bool enabled);
 void ClearGLBindingsGL();
 void SetGLToRealGLApi();
 void SetGLApi(GLApi* api);
+void SetGLApiToNoContext();
 
-class GL_EXPORT GLApiBase : public GLApi {
+class GLApiBase : public GLApi {
  public:
   // Include the auto-generated part of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in
   // this file instead of having to edit some template or the code generator.
   #include "gl_bindings_api_autogen_gl.h"
 
  protected:
   GLApiBase();
   virtual ~GLApiBase();
   void InitializeBase(DriverGL* driver);
 
   DriverGL* driver_;
 };
 
 // Implemenents the GL API by calling directly into the driver.
-class GL_EXPORT RealGLApi : public GLApiBase {
+class RealGLApi : public GLApiBase {
  public:
   RealGLApi();
   virtual ~RealGLApi();
   void Initialize(DriverGL* driver);
 };
 
 // Inserts a TRACE for every GL call.
-class GL_EXPORT TraceGLApi : public GLApi {
+class TraceGLApi : public GLApi {
  public:
   TraceGLApi(GLApi* gl_api) : gl_api_(gl_api) { }
   virtual ~TraceGLApi();
 
   // Include the auto-generated part of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in
   // this file instead of having to edit some template or the code generator.
   #include "gl_bindings_api_autogen_gl.h"
 
  private:
   GLApi* gl_api_;
 };
 
+// Catches incorrect usage when GL calls are made without a current context.
+class NoContextGLApi : public GLApi {
+ public:
+  NoContextGLApi();
+  virtual ~NoContextGLApi();
+
+  // Include the auto-generated part of this class. We split this because
+  // it means we can easily edit the non-auto generated parts right here in
+  // this file instead of having to edit some template or the code generator.
+  #include "gl_bindings_api_autogen_gl.h"
+};
+
 // Implementents the GL API using co-operative state restoring.
 // Assumes there is only one real GL context and that multiple virtual contexts
 // are implemented above it. Restores the needed state from the current context.
-class GL_EXPORT VirtualGLApi : public GLApiBase {
+class VirtualGLApi : public GLApiBase {
  public:
   VirtualGLApi();
   virtual ~VirtualGLApi();
   void Initialize(DriverGL* driver, GLContext* real_context);
 
   // Sets the current virutal context.
   bool MakeCurrent(GLContext* virtual_context, GLSurface* surface);
 
   void OnReleaseVirtuallyCurrent(GLContext* virtual_context);
 
   // Overridden functions from GLApiBase
   virtual const GLubyte* glGetStringFn(GLenum name) OVERRIDE;
 
  private:
   // The real context we're running on.
   GLContext* real_context_;
 
   // The current virtual context.
   GLContext* current_context_;
 
   // The supported extensions being advertised for this virtual context.
   std::string extensions_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_GL_API_IMPLEMENTATION_H_