Support CHROMIUM_path_rendering fragment operations

This brings two new APIs, BindFragmentInputLocation and
ProgramPathFragmentInputGen that together dictate how the
fragment shader varyings are used.

BUG=angleproject:1382

Change-Id: I4b52fd8a3555235a73aecd4f3dba2d500789cbb0
Reviewed-on: https://chromium-review.googlesource.com/357071
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Sami Väisänen <svaisanen@nvidia.com>
Commit-Queue: Sami Väisänen <svaisanen@nvidia.com>
diff --git a/src/libANGLE/renderer/vulkan/ProgramVk.h b/src/libANGLE/renderer/vulkan/ProgramVk.h
index 403a396..8d8a1f7 100644
--- a/src/libANGLE/renderer/vulkan/ProgramVk.h
+++ b/src/libANGLE/renderer/vulkan/ProgramVk.h
@@ -88,6 +88,11 @@
     // Returns false for inactive members.
     bool getUniformBlockMemberInfo(const std::string &memberUniformName,
                                    sh::BlockMemberInfo *memberInfoOut) const override;
+
+    void setPathFragmentInputGen(const std::string &inputName,
+                                 GLenum genMode,
+                                 GLint components,
+                                 const GLfloat *coeffs) override;
 };
 
 }  // namespace rx