Refactor GL tests to use a shader library

Instead of having the same simple shaders repeated over and over in
the test code, reuse a single shader library.

BUG=angleproject:2474
TEST=angle_end2end_tests

Change-Id: I13f8ca8c0125e6d30f1761639bf8c3f69e0e77d2
Reviewed-on: https://chromium-review.googlesource.com/1012078
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/tests/gl_tests/CubeMapTextureTest.cpp b/src/tests/gl_tests/CubeMapTextureTest.cpp
index f6ceae0..514fbc6 100644
--- a/src/tests/gl_tests/CubeMapTextureTest.cpp
+++ b/src/tests/gl_tests/CubeMapTextureTest.cpp
@@ -25,27 +25,13 @@
     {
         ANGLETest::SetUp();
 
-        const std::string vsSource =
-            R"(attribute highp vec4 position;
-            void main(void)
-            {
-                gl_Position = position;
-            })";
-
-        const std::string fsSource =
-            R"(uniform highp vec4 color;
-            void main(void)
-            {
-                gl_FragColor = color;
-            })";
-
-        mProgram = CompileProgram(vsSource, fsSource);
+        mProgram = CompileProgram(essl1_shaders::vs::Simple(), essl1_shaders::fs::UniformColor());
         if (mProgram == 0)
         {
             FAIL() << "shader compilation failed.";
         }
 
-        mColorLocation = glGetUniformLocation(mProgram, "color");
+        mColorLocation = glGetUniformLocation(mProgram, essl1_shaders::ColorUniform());
 
         glUseProgram(mProgram);
 
@@ -108,7 +94,7 @@
         const GLfloat *faceColor = faceColors + (face * 4);
         glUniform4f(mColorLocation, faceColor[0], faceColor[1], faceColor[2], faceColor[3]);
 
-        drawQuad(mProgram, "position", 0.5f);
+        drawQuad(mProgram, essl1_shaders::PositionAttrib(), 0.5f);
         EXPECT_GL_NO_ERROR();
     }