Expose Null ANGLE backend

ui/gl/gl_surface_egl.cc

Index: ui/gl/gl_surface_egl.cc
diff --git a/ui/gl/gl_surface_egl.cc b/ui/gl/gl_surface_egl.cc
index c54aa7048618b28c3a54d8ebb8b9af65646f6e79..e5f208162982e04f65a87f6ed738085d6e1ec284 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -77,6 +77,11 @@ extern "C" {
 #define EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE 0x320E
 #endif /* EGL_ANGLE_platform_angle_opengl */
 
+#ifndef EGL_ANGLE_platform_angle_null
+#define EGL_ANGLE_platform_angle_null 1
+#define EGL_PLATFORM_ANGLE_TYPE_NULL_ANGLE 0x33AE
+#endif /* EGL_ANGLE_platform_angle_null */
+
 #ifndef EGL_ANGLE_x11_visual
 #define EGL_ANGLE_x11_visual 1
 #define EGL_X11_VISUAL_ID_ANGLE 0x33A3
@@ -173,6 +178,9 @@ EGLDisplay GetDisplayFromType(DisplayType display_type,
     case ANGLE_OPENGLES:
       return GetPlatformANGLEDisplay(
           native_display, EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE, false);
+    case ANGLE_NULL:
+      return GetPlatformANGLEDisplay(
+          native_display, EGL_PLATFORM_ANGLE_TYPE_NULL_ANGLE, false);
     default:
       NOTREACHED();
       return EGL_NO_DISPLAY;
@@ -193,6 +201,8 @@ const char* DisplayTypeString(DisplayType display_type) {
       return "OpenGL";
     case ANGLE_OPENGLES:
       return "OpenGLES";
+    case ANGLE_NULL:
+      return "Null";
     default:
       NOTREACHED();
       return "Err";
@@ -363,6 +373,9 @@ void GetEGLInitDisplays(bool supports_angle_d3d,
       !command_line->HasSwitch(switches::kUseANGLE) ||
       requested_renderer == kANGLEImplementationDefaultName;
 
+  if (requested_renderer == kANGLEImplementationNullName)

[Geoff Lang, 2016/10/19 16:23:09]

We should check for the extension first.

[piman, 2016/10/19 18:03:01]

Done.

+    init_displays->push_back(ANGLE_NULL);
+
   if (supports_angle_d3d) {
     if (use_angle_default) {
       // Default mode for ANGLE - try D3D11, else try D3D9