Remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/)

src/core/SkValidatingReadBuffer.cpp

Index: src/core/SkValidatingReadBuffer.cpp
diff --git a/src/core/SkValidatingReadBuffer.cpp b/src/core/SkValidatingReadBuffer.cpp
index 0112f18ec44d5b922d9a0e4455e6975b371577df..96f20a24833b7e23b7e34d54aa58fa28f45a848d 100644
--- a/src/core/SkValidatingReadBuffer.cpp
+++ b/src/core/SkValidatingReadBuffer.cpp
@@ -273,3 +273,15 @@ SkFlattenable* SkValidatingReadBuffer::readFlattenable(SkFlattenable::Type type)
     }
     return obj;
 }
+
+void SkValidatingReadBuffer::skipFlattenable() {
+    SkString name;
+    this->readString(&name);
+    if (fError) {
+        return;
+    }
+    uint32_t sizeRecorded = this->readUInt();
+    this->skip(sizeRecorded);
+}
+
+