Tracking uniform ownership

This is a prerequisite change for the upcoming sample(child, matrix)
function. By itself, this CL doesn't really change anything; it just
adds an ownership tracking feature which sample(child, matrix) depends
on.

Change-Id: I98b12e5fb062a2535af367931e7a932ea9c63a59
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/281337
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/gpu/GrPathProcessor.cpp b/src/gpu/GrPathProcessor.cpp
index b365740..1c5f56e 100644
--- a/src/gpu/GrPathProcessor.cpp
+++ b/src/gpu/GrPathProcessor.cpp
@@ -42,7 +42,8 @@
 
         // Setup uniform color
         const char* stagedLocalVarName;
-        fColorUniform = args.fUniformHandler->addUniform(kFragment_GrShaderFlag,
+        fColorUniform = args.fUniformHandler->addUniform(nullptr,
+                                                         kFragment_GrShaderFlag,
                                                          kHalf4_GrSLType,
                                                          "Color",
                                                          &stagedLocalVarName);
@@ -81,7 +82,8 @@
                         uni.fType = kFloat3x3_GrSLType;
                     }
                     uni.fHandle = uniformHandler
-                                          ->addUniform(kFragment_GrShaderFlag,
+                                          ->addUniform(nullptr,
+                                                       kFragment_GrShaderFlag,
                                                        uni.fType,
                                                        strUniName.c_str(),
                                                        &name)