re-re-land of skslc now automatically turns on derivatives support

src/gpu/gl/builders/GrGLShaderStringBuilder.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLShaderStringBuilder.h"
 #include "gl/GrGLGpu.h"
 #include "gl/GrGLSLPrettyPrint.h"
@@ skipping 67 matching lines @@
             result.fVersion = 310;
             break;
         case k320es_GrGLSLGeneration:
             SkASSERT(kGLES_GrGLStandard == standard);
             result.fVersion = 320;
             break;
     }
     result.fIsCoreProfile = caps->isCoreProfile();
     result.fUsesPrecisionModifiers = glslCaps->usesPrecisionModifiers();
     result.fMustDeclareFragmentShaderOutput = glslCaps->mustDeclareFragmentShaderOutput();
+    result.fShaderDerivativeSupport = glslCaps->shaderDerivativeSupport();
+    if (result.fShaderDerivativeSupport && glslCaps->shaderDerivativeExtensionString()) {
+        result.fShaderDerivativeExtensionString = glslCaps->shaderDerivativeExtensionString();
+    }
     result.fCanUseMinAndAbsTogether = glslCaps->canUseMinAndAbsTogether();
     result.fMustForceNegatedAtanParamToFloat = glslCaps->mustForceNegatedAtanParamToFloat();
     return result;
 }
 
 static void dump_string(std::string s) {
     // on Android, SkDebugf only displays the first 1K characters of output, which results in
     // incomplete shader source code. Print each line individually to avoid this problem.
     size_t index = 0;
     for (;;) {
@@ skipping 115 matching lines @@
 
 static void print_shader_source(const char** strings, int* lengths, int count) {
     const SkString& pretty = GrGLSLPrettyPrint::PrettyPrintGLSL(strings, lengths, count, true);
     SkTArray<SkString> lines;
     SkStrSplit(pretty.c_str(), "\n", &lines);
     for (const SkString& line : lines) {
         // Print the shader one line at the time so it doesn't get truncated by the adb log.
         SkDebugf("%s\n", line.c_str());
     }
 }