Make GrGLConfigConversionEffect work for Imagination and some other GPUs.

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 c5df4c803ce501011616bef7c7d458d1668d8996..be10594c85d950f5189b5f28728ce0544100a519 100644
--- a/src/gpu/gl/GrGLShaderBuilder.cpp
+++ b/src/gpu/gl/GrGLShaderBuilder.cpp
@@ -693,9 +693,17 @@ static GrGLuint attach_shader(const GrGLContext& glCtx,
 bool GrGLShaderBuilder::compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const {
     SkString fragShaderSrc(GrGetGLSLVersionDecl(this->ctxInfo()));
     fragShaderSrc.append(fFSExtensions);
-    append_default_precision_qualifier(kDefaultFragmentPrecision,
-                                       fGpu->glStandard(),
-                                       &fragShaderSrc);
+
+    if (kImagination_GrGLVendor == this->ctxInfo().vendor() &&
+        kPVRRogueHood_GrGLRenderer == this->ctxInfo().renderer())
+      append_default_precision_qualifier(GrGLShaderVar::kHigh_Precision,

[bsalomon, 2014/06/09 13:56:45]

Can you not just apply highp to the vars emitted by the config conversion
effect? Does this make any other shaders work better?

[changjun.yang, 2014/06/10 11:41:17]

Thanks! Pls see my comments above.

+                                         fGpu->glStandard(),
+                                         &fragShaderSrc);
+    else
+      append_default_precision_qualifier(kDefaultFragmentPrecision,
+                                         fGpu->glStandard(),
+                                         &fragShaderSrc);
+
     this->appendUniformDecls(kFragment_Visibility, &fragShaderSrc);
     this->appendDecls(fFSInputs, &fragShaderSrc);
     // We shouldn't have declared outputs on 1.10