Add support for GL_TEXTURE_EXTERNAL_OES NV12 textures in cc/

cc/output/shader.cc

Index: cc/output/shader.cc
diff --git a/cc/output/shader.cc b/cc/output/shader.cc
index 2adc9a7e1fd7247290d63a41d6fb78a3bbac4b5a..5df5a3c4d3f8b4ab7ff50717c4653733e8c0fe49 100644
--- a/cc/output/shader.cc
+++ b/cc/output/shader.cc
@@ -133,7 +133,8 @@ static std::string SetFragmentSamplerType(SamplerType requested_type,
     case SAMPLER_TYPE_EXTERNAL_OES:
       DCHECK_NE(shader_string.find("SamplerType"), std::string::npos);
       DCHECK_NE(shader_string.find("TextureLookup"), std::string::npos);
-      return "#extension GL_OES_EGL_image_external : require\n"
+      return "#extension GL_OES_EGL_image_external : enable\n"
+             "#extension GL_NV_EGL_stream_consumer_external : enable\n"
              "#define SamplerType samplerExternalOES\n"
              "#define TextureLookup texture2D\n" +
              shader_string;