IWYU: 'core' target, files starting A-C.

TBR=reed@google.com
Verbal lgtm, does not change API.

Committed: https://skia.googlesource.com/skia/+/7403d87db8e43d4c2b5b25ac22a0ebc22bd09d69

Review URL: https://codereview.chromium.org/1265033002
diff --git a/src/core/SkColor.cpp b/src/core/SkColor.cpp
index 6fa239f..73e6ddd 100644
--- a/src/core/SkColor.cpp
+++ b/src/core/SkColor.cpp
@@ -1,4 +1,3 @@
-
 /*
  * Copyright 2006 The Android Open Source Project
  *
@@ -6,9 +5,9 @@
  * found in the LICENSE file.
  */
 
-
 #include "SkColor.h"
 #include "SkColorPriv.h"
+#include "SkFixed.h"
 
 SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
     return SkPremultiplyARGBInline(a, r, g, b);