Add isSingleComponent bool to getConstantColorComponent

src/gpu/GrProcessor.cpp

Index: src/gpu/GrProcessor.cpp
diff --git a/src/gpu/GrProcessor.cpp b/src/gpu/GrProcessor.cpp
index 45298b522d3ef9e1bf367c19ea8989a8b02f900e..efde081f5a9a326ea625ae6343dec7d3f44d1a37 100644
--- a/src/gpu/GrProcessor.cpp
+++ b/src/gpu/GrProcessor.cpp
@@ -88,4 +88,17 @@ void GrProcessor::assertEquality(const GrProcessor& other) const {
         SkASSERT(this->textureAccess(i) == other.textureAccess(i));
     }
 }
+
+void GrProcessor::validateComponents(GrColor color, uint32_t validFlags,
+                                     bool isSingleComponent) const {
+    if (isSingleComponent) {
+        SkASSERT(0 == validFlags || kRGBA_GrColorComponentFlags == validFlags);
+        if (kRGBA_GrColorComponentFlags == validFlags) {
+            unsigned colorA = GrColorUnpackA(color);
+            SkASSERT(GrColorUnpackR(color) == colorA &&
+                     GrColorUnpackG(color) == colorA &&
+                     GrColorUnpackB(color) == colorA);
+        }
+    }
+}
 #endif