Disable GLVirtualContextsEXTWindowRectanglesTest for some devices

The test is causing crash on devices which do not suport OpenGL ES3.

Bug: 644265
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Id98475c27897e1ca4cd207af4d145ab0c4733a85
Reviewed-on: https://chromium-review.googlesource.com/788112Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519765}

gpu/command_buffer/tests/gl_virtual_contexts_ext_window_rectangles_unittest.cc

@@ -32,12 +32,13 @@ class GLVirtualContextsEXTWindowRectanglesTest : public testing::Test {
   }
 
   bool IsApplicable() const {
-    // If a driver isn't capable of supporting ES3 context, creating
-    // ContextGroup will fail.
-    bool have_es3 = gl_real_shared_.decoder() &&
-                    gl_real_shared_.decoder()->GetContextGroup();
+    // Not applicable for devices not supporting OpenGLES3.
+    if (!gl_real_shared_.IsInitialized()) {
+      return false;
+    }
+
     bool have_ext = GLTestHelper::HasExtension("GL_EXT_window_rectangles");
-    return have_es3 && have_ext;
+    return have_ext;
   }
 
   GLManager gl_real_shared_;