Implement support for CHROMIUM_NV_path_rendering pseudo extension

src/gpu/gl/GrGLShaderBuilder.cpp

Index: src/gpu/gl/GrGLShaderBuilder.cpp
diff --git a/src/gpu/gl/GrGLShaderBuilder.cpp b/src/gpu/gl/GrGLShaderBuilder.cpp
index b72e23f9ba20b10879c70b6c48c52324ec288cf7..437f6147e4d148ba7b4268e14375b6549ad632de 100644
--- a/src/gpu/gl/GrGLShaderBuilder.cpp
+++ b/src/gpu/gl/GrGLShaderBuilder.cpp
@@ -186,6 +186,15 @@ bool GrGLShaderBuilder::enableFeature(GLSLFeature feature) {
                                    "GL_OES_standard_derivatives");
             }
             return true;
+        case kTexCoordSupport_GLSLFeature:
+            if (!fGpu->glCaps().pathRenderingSupport()) {
+                return false;
+            }
+            if (kGLES_GrGLStandard == fGpu->glStandard()) {
+                this->addFSFeature(1 << kTexCoordSupport_GLSLFeature,
+                                   "GL_CHROMIUM_path_rendering");
+            }
+            return true;
         default:
             GrCrash("Unexpected GLSLFeature requested.");
             return false;
@@ -976,6 +985,7 @@ GrGLFragmentOnlyShaderBuilder::GrGLFragmentOnlyShaderBuilder(GrGpuGL* gpu,
 }
 
 int GrGLFragmentOnlyShaderBuilder::addTexCoordSets(int count) {
+    SkAssertResult(this->enableFeature(kTexCoordSupport_GLSLFeature));
     int firstFreeCoordSet = fNumTexCoordSets;
     fNumTexCoordSets += count;
     SkASSERT(gpu()->glCaps().maxFixedFunctionTextureCoords() >= fNumTexCoordSets);
@@ -997,3 +1007,21 @@ GrGLProgramEffects* GrGLFragmentOnlyShaderBuilder::createAndEmitEffects(
                                           inOutFSColor);
     return pathTexGenEffectsBuilder.finish();
 }
+
+bool GrGLFragmentOnlyShaderBuilder::compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const {
+    // Command buffer does not support vertexshader-less programs.
+    // Use a dummy shader.
+    const GrGLContext& glCtx = this->gpu()->glContext();
+    SkString vertShaderSrc(GrGetGLSLVersionDecl(this->ctxInfo()));
+    vertShaderSrc.append("void main() {\n");
+    vertShaderSrc.append("gl_Position = vec4(1);");
+    vertShaderSrc.append("}\n");
+    GrGLuint vertShaderId = attach_shader(glCtx, programId, GR_GL_VERTEX_SHADER, vertShaderSrc);
+    if (!vertShaderId) {
+        return false;
+    }
+    *shaderIds->append() = vertShaderId;
+
+    return this->INHERITED::compileAndAttachShaders(programId, shaderIds);
+}
+