headless: Enable GL support by default

headless/lib/headless_browser_browsertest.cc

 // Copyright 2016 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.
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "content/public/test/browser_test.h"
 #include "headless/public/domains/page.h"
@@ skipping 141 matching lines @@
   EXPECT_TRUE(WaitForLoad(web_contents));
 
   std::string inner_html;
   EXPECT_TRUE(EvaluateScript(web_contents, "document.body.innerHTML")
                   ->GetResult()
                   ->GetValue()
                   ->GetAsString(&inner_html));
   EXPECT_EQ(kResponseBody, inner_html);
 }
 
+IN_PROC_BROWSER_TEST_F(HeadlessBrowserTest, WebGLSupported) {
+  HeadlessWebContents* web_contents =
+      browser()->CreateWebContentsBuilder().Build();
+
+  bool webgl_supported;
+  EXPECT_TRUE(EvaluateScript(
+      web_contents,
+      "(document.createElement('canvas').getContext('webgl')"
+      "    instanceof WebGLRenderingContext)")
+                  ->GetResult()
+                  ->GetValue()
+                  ->GetAsBoolean(&webgl_supported));
+  EXPECT_TRUE(webgl_supported);
+}
+
 }  // namespace headless