Everyone gets a namespace {}.

src/opts/SkPMFloat_neon.h

Index: src/opts/SkPMFloat_neon.h
diff --git a/src/opts/SkPMFloat_neon.h b/src/opts/SkPMFloat_neon.h
index 1c01bc48038c6a22637ef18ced9b3ac793a19e08..cabb29a2a80ee8b399878a21e26aa723f0c90e31 100644
--- a/src/opts/SkPMFloat_neon.h
+++ b/src/opts/SkPMFloat_neon.h
@@ -5,6 +5,8 @@
  * found in the LICENSE file.
  */
 
+namespace { // See SkPMFloat.h
+
 // For SkPMFloat(SkPMFColor), we widen our 8 bit components (fix8) to 8-bit components in 16 bits
 // (fix8_16), then widen those to 8-bit-in-32-bits (fix8_32), and finally convert those to floats.
 
@@ -70,3 +72,5 @@ inline void SkPMFloat::RoundClampTo4PMColors(
     colors[2] = c.roundClamp();
     colors[3] = d.roundClamp();
 }
+
+}  // namespace