Distance field fixes for Android

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index a60230a2fe91de7e744a27a002cac988e6b3f912..47f3f0f0c819d6fd97312bd4cb424ebe42369d92 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -47,6 +47,7 @@ void GrGLCaps::reset() {
     fFixedFunctionSupport = false;
     fDiscardFBSupport = false;
     fFullClearIsFree = false;
+    fDropsTileOnZeroDivide = false;
 }
 
 GrGLCaps::GrGLCaps(const GrGLCaps& caps) : GrDrawTargetCaps() {
@@ -84,6 +85,7 @@ GrGLCaps& GrGLCaps::operator = (const GrGLCaps& caps) {
     fFixedFunctionSupport = caps.fFixedFunctionSupport;
     fDiscardFBSupport = caps.fDiscardFBSupport;
     fFullClearIsFree = caps.fFullClearIsFree;
+    fDropsTileOnZeroDivide = caps.fDropsTileOnZeroDivide;
 
     return *this;
 }
@@ -244,6 +246,9 @@ void GrGLCaps::init(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
         }
     }
 
+    // Adreno GPUs have a tendency to drop tiles when there is a divide-by-zero in a shader
+    fDropsTileOnZeroDivide = kQualcomm_GrGLVendor == ctxInfo.vendor();
+
     this->initFSAASupport(ctxInfo, gli);
     this->initStencilFormats(ctxInfo);
 
@@ -661,5 +666,6 @@ SkString GrGLCaps::dump() const {
              (fUseNonVBOVertexAndIndexDynamicData ? "YES" : "NO"));
     r.appendf("Discard FrameBuffer support: %s\n", (fDiscardFBSupport ? "YES" : "NO"));
     r.appendf("Full screen clear is free: %s\n", (fFullClearIsFree ? "YES" : "NO"));
+    r.appendf("Drops tile on zero divide: %s\n", (fDropsTileOnZeroDivide ? "YES" : "NO"));
     return r;
 }