Check GL context creation succeeds before using the context.

BUG=902684
TEST=bots
R=piman@chromium.org

Change-Id: I0c7267b6c23313e9613d38ecdf399707cbd8b11c
Reviewed-on: https://chromium-review.googlesource.com/c/1338494
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608627}

ui/gl/gl_surface_egl.cc

@@ -737,7 +737,7 @@ bool GLSurfaceEGL::InitializeOneOffCommon() {
     scoped_refptr<GLSurface> surface = new SurfacelessEGL(gfx::Size(1, 1));
     scoped_refptr<GLContext> context = InitializeGLContext(
         new GLContextEGL(nullptr), surface.get(), GLContextAttribs());
-    if (!context->MakeCurrent(surface.get()))
+    if (!context || !context->MakeCurrent(surface.get()))
       g_egl_surfaceless_context_supported = false;
 
     // Ensure context supports GL_OES_surfaceless_context.