cc: Remove code for drawing checkerboard quads, it's not used.

cc/output/shader.cc

Index: cc/output/shader.cc
diff --git a/cc/output/shader.cc b/cc/output/shader.cc
index 15ad7e05fa71224363e5176b35d5973434aef155..4a877ae859f6e6da9bcd4d759881fdfe78e45f00 100644
--- a/cc/output/shader.cc
+++ b/cc/output/shader.cc
@@ -2253,64 +2253,4 @@ std::string FragmentShaderColorAA::GetShaderBody() {
   });
 }
 
-FragmentShaderCheckerboard::FragmentShaderCheckerboard()
-    : alpha_location_(-1),
-      tex_transform_location_(-1),
-      frequency_location_(-1) {
-}
-
-void FragmentShaderCheckerboard::Init(GLES2Interface* context,
-                                      unsigned program,
-                                      int* base_uniform_index) {
-  static const char* uniforms[] = {
-      "alpha", "texTransform", "frequency", "color",
-  };
-  int locations[arraysize(uniforms)];
-
-  GetProgramUniformLocations(context,
-                             program,
-                             arraysize(uniforms),
-                             uniforms,
-                             locations,
-                             base_uniform_index);
-  alpha_location_ = locations[0];
-  tex_transform_location_ = locations[1];
-  frequency_location_ = locations[2];
-  color_location_ = locations[3];
-}
-
-std::string FragmentShaderCheckerboard::GetShaderString(
-    TexCoordPrecision precision,
-    SamplerType sampler) const {
-  return FRAGMENT_SHADER(GetShaderHead(), GetShaderBody());
-}
-
-std::string FragmentShaderCheckerboard::GetShaderHead() {
-  return SHADER0([]() {
-    precision mediump float;
-    precision mediump int;
-    varying vec2 v_texCoord;
-    uniform float alpha;
-    uniform float frequency;
-    uniform vec4 texTransform;
-    uniform vec4 color;
-  });
-}
-
-std::string FragmentShaderCheckerboard::GetShaderBody() {
-  // Shader based on Example 13-17 of "OpenGL ES 2.0 Programming Guide"
-  // by Munshi, Ginsburg, Shreiner.
-  return SHADER0([]() {
-    void main() {
-      vec4 color1 = vec4(1.0, 1.0, 1.0, 1.0);
-      vec4 color2 = color;
-      vec2 texCoord =
-          clamp(v_texCoord, 0.0, 1.0) * texTransform.zw + texTransform.xy;
-      vec2 coord = mod(floor(texCoord * frequency * 2.0), 2.0);
-      float picker = abs(coord.x - coord.y);  // NOLINT
-      gl_FragColor = mix(color1, color2, picker) * alpha;
-    }
-  });
-}
-
 }  // namespace cc