Implement support for CHROMIUM_path_rendering pseudo extension

Implement support for path rendering in Chromium through
CHROMIUM_path_rendering pseudo extension.

The extension defines a new pseudo-gl function,
BindFragmentInputLocation. This behaves similarly to the
BindUniformLocation pseudo-gl function. The idea is to assign fragment
input location to a fragment input before linking the program.

BUG=chromium:344330

Committed: https://skia.googlesource.com/skia/+/eeef46d181f9f8db388ecea81df699fc1b3c9280

Review URL: https://codereview.chromium.org/1192663002
diff --git a/src/gpu/gl/GrGLPathRendering.cpp b/src/gpu/gl/GrGLPathRendering.cpp
index ffdbbda..7c77155 100644
--- a/src/gpu/gl/GrGLPathRendering.cpp
+++ b/src/gpu/gl/GrGLPathRendering.cpp
@@ -61,6 +61,9 @@
 
 GrGLPathRendering::GrGLPathRendering(GrGLGpu* gpu)
     : GrPathRendering(gpu) {
+    const GrGLInterface* glInterface = gpu->glInterface();
+    fCaps.bindFragmentInputSupport =
+        NULL != glInterface->fFunctions.fBindFragmentInputLocation;
 }
 
 GrGLPathRendering::~GrGLPathRendering() {