Revert "Revert "Allow FPs to elevate default precision for the entire fragment program""

This reverts commit 903c3f70400462e191ccbca63393b2df3fe2dd11.

Reason for revert: Vulkan issue fixed in compiler.

Original change's description:
> Revert "Allow FPs to elevate default precision for the entire fragment program"
> 
> This reverts commit 92d7ccafdf896cf19764e025873d13315a76842d.
> 
> Reason for revert: Vulkan errors.
> 
> Original change's description:
> > Allow FPs to elevate default precision for the entire fragment program
> > 
> > Currently, GrConfigConversionEffect is able to round-trip on many mobile
> > GPUs because it uses highp for all intermediate variables (including the
> > texture fetch result). Separating the texture sample into a different
> > processor breaks that.
> > 
> > This is a blunt instrument, not to be used lightly.
> > 
> > Bug: skia:
> > Change-Id: I2ab365e3da79628069e2eb727c43c2bf45bfd789
> > Reviewed-on: https://skia-review.googlesource.com/10162
> > Reviewed-by: Brian Salomon <bsalomon@google.com>
> > Commit-Queue: Brian Osman <brianosman@google.com>
> > 
> 
> TBR=bsalomon@google.com,robertphillips@google.com,brianosman@google.com,ethannicholas@google.com,reviews@skia.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> 
> Change-Id: Iee5bb409f86a9cabecc76bd1273a5b3cef6af179
> Reviewed-on: https://skia-review.googlesource.com/10967
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
> 

TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org,brianosman@google.com,ethannicholas@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I733a0ecc40b58d8727f0259b5498c8e6610cedce
Reviewed-on: https://skia-review.googlesource.com/11010
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/private/GrGLSL.h b/include/private/GrGLSL.h
index ed33c1cf4c..66f7be84d1 100644
--- a/include/private/GrGLSL.h
+++ b/include/private/GrGLSL.h
@@ -74,6 +74,8 @@ static inline const char* GrGLSLPrecisionString(GrSLPrecision p) {
             return "mediump";
         case kHigh_GrSLPrecision:
             return "highp";
+        case kDefault_GrSLPrecision:
+            return "";
         default:
             SkFAIL("Unexpected precision type.");
             return "";