Add a workaround for copyTexImage2D as it is sometimes broken on OSX.

gpu/command_buffer/tests/gl_test_utils.cc

Index: gpu/command_buffer/tests/gl_test_utils.cc
diff --git a/gpu/command_buffer/tests/gl_test_utils.cc b/gpu/command_buffer/tests/gl_test_utils.cc
index 4878b1489c0783b9038087c5b8fb24bb04054202..d9a30ce9b96b10b6a12d4387597c237375b6c285 100644
--- a/gpu/command_buffer/tests/gl_test_utils.cc
+++ b/gpu/command_buffer/tests/gl_test_utils.cc
@@ -4,19 +4,71 @@
 
 #include "gpu/command_buffer/tests/gl_test_utils.h"
 
+#include <GLES2/gl2extchromium.h>
 #include <stdint.h>
 #include <stdio.h>
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/strings/stringize_macros.h"
+#include "base/strings/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/geometry/size.h"
 
 // GCC requires these declarations, but MSVC requires they not be present.
 #ifndef COMPILER_MSVC
 const uint8_t GLTestHelper::kCheckClearValue;
 #endif
 
+// Compiles a fragment shader for sampling out of a texture of |size| bound to
+// |target| and checks for compilation errors.
+GLuint LoadFragmentShader(unsigned target, const gfx::Size& size) {
+  // clang-format off
+  const char kFragmentShader[] = STRINGIZE(
+    uniform SamplerType a_texture;
+    varying vec2 v_texCoord;
+    void main() {
+      gl_FragColor = TextureLookup(a_texture, v_texCoord * TextureScale);
+    }
+  );
+  const char kShaderFloatPrecision[] = STRINGIZE(
+    precision mediump float;
+  );
+  // clang-format on
+
+  switch (target) {
+    case GL_TEXTURE_2D:
+      return GLTestHelper::LoadShader(
+          GL_FRAGMENT_SHADER,
+          base::StringPrintf("%s\n"
+                             "#define SamplerType sampler2D\n"
+                             "#define TextureLookup texture2D\n"
+                             "#define TextureScale vec2(1.0, 1.0)\n"
+                             "%s",
+                             kShaderFloatPrecision,
+                             kFragmentShader)
+              .c_str());
+    case GL_TEXTURE_RECTANGLE_ARB:
+      return GLTestHelper::LoadShader(
+          GL_FRAGMENT_SHADER,
+          base::StringPrintf("%s\n"
+                             "#extension GL_ARB_texture_rectangle : require\n"
+                             "#define SamplerType sampler2DRect\n"
+                             "#define TextureLookup texture2DRect\n"
+                             "#define TextureScale vec2(%f, %f)\n"
+                             "%s",
+                             kShaderFloatPrecision,
+                             static_cast<double>(size.width()),
+                             static_cast<double>(size.height()),
+                             kFragmentShader)
+              .c_str());
+    default:
+      NOTREACHED();
+      return 0;
+  }
+}
+
 bool GLTestHelper::HasExtension(const char* extension) {
   std::string extensions(
       reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS)));
@@ -259,3 +311,35 @@ bool GLTestHelper::SaveBackbufferAsBMP(
   fclose(fp);
   return true;
 }
+
+void GLTestHelper::DrawTextureQuad(GLenum target, const gfx::Size& size) {
+  // clang-format off
+  const char kVertexShader[] = STRINGIZE(
+    attribute vec2 a_position;
+    varying vec2 v_texCoord;
+    void main() {
+      gl_Position = vec4(a_position.x, a_position.y, 0.0, 1.0);
+      v_texCoord = (a_position + vec2(1.0, 1.0)) * 0.5;
+    }
+  );
+  // clang-format on
+
+  // Setup program.
+  GLuint vertex_shader =
+      GLTestHelper::LoadShader(GL_VERTEX_SHADER, kVertexShader);
+  GLuint fragment_shader = LoadFragmentShader(target, size);
+  GLuint program = GLTestHelper::SetupProgram(vertex_shader, fragment_shader);
+  EXPECT_NE(program, 0u);
+  glUseProgram(program);
+
+  GLint sampler_location = glGetUniformLocation(program, "a_texture");
+  ASSERT_NE(sampler_location, -1);
+
+  GLuint vertex_buffer = GLTestHelper::SetupUnitQuad(sampler_location);
+  glDrawArrays(GL_TRIANGLES, 0, 6);
+
+  glDeleteShader(vertex_shader);
+  glDeleteShader(fragment_shader);
+  glDeleteProgram(program);
+  glDeleteBuffers(1, &vertex_buffer);
+}