Refactor DrawTextureQuad and CheckPixels in gl_tests util

gpu/command_buffer/tests/gl_ext_srgb_unittest.cc

Index: gpu/command_buffer/tests/gl_ext_srgb_unittest.cc
diff --git a/gpu/command_buffer/tests/gl_ext_srgb_unittest.cc b/gpu/command_buffer/tests/gl_ext_srgb_unittest.cc
index 139f8e646b6b8d18697fbe8a61ce03954cc6dd68..a576d413d32eb68030be1e210724fa9ce5570399 100644
--- a/gpu/command_buffer/tests/gl_ext_srgb_unittest.cc
+++ b/gpu/command_buffer/tests/gl_ext_srgb_unittest.cc
@@ -66,10 +66,10 @@ TEST_F(GLEXTSRGBTest, TexImageSRGBALPHAFormat) {
   EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
             glCheckFramebufferStatus(GL_FRAMEBUFFER));
 
-  GLTestHelper::CheckPixels(0, 0, kSubImageX, kHeight, 0, kImageColor);
-  GLTestHelper::CheckPixels(0, 0, kWidth, kSubImageY, 0, kImageColor);
+  GLTestHelper::CheckPixels(0, 0, kSubImageX, kHeight, 0, kImageColor, nullptr);
+  GLTestHelper::CheckPixels(0, 0, kWidth, kSubImageY, 0, kImageColor, nullptr);
   GLTestHelper::CheckPixels(kSubImageX, kSubImageY, kSubImageWidth,
-                            kSubImageHeight, 0, kSubImageColor);
+                            kSubImageHeight, 0, kSubImageColor, nullptr);
 }
 
 }  // namespace gpu