Expose Null ANGLE backend

ui/gl/gl_surface_egl.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_SURFACE_EGL_H_
 #define UI_GL_GL_SURFACE_EGL_H_
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
@@ skipping 20 matching lines @@
 // If adding a new type, also add it to EGLDisplayType in
 // tools/metrics/histograms/histograms.xml. Don't remove or reorder entries.
 enum DisplayType {
   DEFAULT = 0,
   SWIFT_SHADER = 1,
   ANGLE_WARP = 2,
   ANGLE_D3D9 = 3,
   ANGLE_D3D11 = 4,
   ANGLE_OPENGL = 5,
   ANGLE_OPENGLES = 6,
-  DISPLAY_TYPE_MAX = 7,
+  ANGLE_NULL = 7,
+  DISPLAY_TYPE_MAX = 8,
 };
 
 GL_EXPORT void GetEGLInitDisplays(bool supports_angle_d3d,
                                   bool supports_angle_opengl,
+                                  bool supports_angle_null,
                                   const base::CommandLine* command_line,
                                   std::vector<DisplayType>* init_displays);
 
 // VSync provider for EGL surface;
 class GL_EXPORT EGLSyncControlVSyncProvider : public SyncControlVSyncProvider {
  public:
   explicit EGLSyncControlVSyncProvider(EGLSurface surface);
   ~EGLSyncControlVSyncProvider() override;
 
  protected:
@@ skipping 178 matching lines @@
   ~SurfacelessEGL() override;
 
  private:
   gfx::Size size_;
   DISALLOW_COPY_AND_ASSIGN(SurfacelessEGL);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_SURFACE_EGL_H_