Fix gpu mipmap support on ChromeOS

gpu/command_buffer/tests/gl_bgra_mipmap_unittest.cc

+// Copyright (c) 2015 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 <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <stdint.h>
+
+#include "gpu/command_buffer/tests/gl_manager.h"
+#include "gpu/command_buffer/tests/gl_test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace gpu {
+
+// A collection of tests that exercise the GL_EXT_srgb extension.
+class GLBGRAMipMapTest : public testing::Test {
+ protected:
+  void SetUp() override { gl_.Initialize(GLManager::Options()); }
+  void TearDown() override { gl_.Destroy(); }
+  GLManager gl_;
+};
+
+// Test to ensure that using GL_BGRA as a texture internal format does
+// not hinder the use of mipmaps. Support for GL_BGRA as an internal format
+// is required by ES 2.0 (internal format must be equal to external format),
+// but some desktop GL implementations may not fully support the use of
+// GL_BGRA. For example, Mesa+Intel does not support mipmapping on textures
+// that use the GL_BGRA internal format. This test verifies a workaround.
+TEST_F(GLBGRAMipMapTest, GenerateMipmapsSucceeds) {
+  static const int kWidth = 100;
+  static const int kHeight = 50;
+
+  uint8_t pixels[kWidth * kHeight * 4];
+
+  GLuint tex = 0;
+  glGenTextures(1, &tex);
+  glBindTexture(GL_TEXTURE_2D, tex);
+
+  memset(pixels, 128, sizeof(pixels));
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_BGRA_EXT, kWidth, kHeight, 0,
+               GL_BGRA_EXT, GL_UNSIGNED_BYTE, pixels);
+  EXPECT_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
+
+  // Without the workaround, the following call generates a
+  // GL_INVALID_OPERATION error on some desktop GL implementations
+  glGenerateMipmap(GL_TEXTURE_2D);
+  EXPECT_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
+}
+
+}  // namespace gpu