IWYU for test files starting with 'A'.

While testing some changes to iwyu, started fixing some files. Made it
to AsADashTest.cpp before running into
https://github.com/include-what-you-use/include-what-you-use/issues/364

Change-Id: I42b65df4f1f8116e0ea1b2cd774651990db1b132
Reviewed-on: https://skia-review.googlesource.com/111861
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/tests/ApplyGammaTest.cpp b/tests/ApplyGammaTest.cpp
index 4147be7..8eb35e1 100644
--- a/tests/ApplyGammaTest.cpp
+++ b/tests/ApplyGammaTest.cpp
@@ -5,16 +5,31 @@
  * found in the LICENSE file.
  */
 
-#include <initializer_list>
-#include "Test.h"
+#include "SkTypes.h"
 
 #if SK_SUPPORT_GPU
-#include "GrContext.h"
 
+#include "GrCaps.h"
+#include "GrContext.h"
+#include "GrContextFactory.h"
+#include "GrShaderCaps.h"
+#include "GrTypes.h"
+#include "SkBitmap.h"
+#include "SkBlendMode.h"
 #include "SkCanvas.h"
+#include "SkColor.h"
 #include "SkColorFilter.h"
+#include "SkColorPriv.h"
+#include "SkImageInfo.h"
+#include "SkPaint.h"
+#include "SkRefCnt.h"
+#include "SkScalar.h"
 #include "SkSurface.h"
+#include "SkTemplates.h"
 #include "SkUtils.h"
+#include "Test.h"
+
+#include <math.h>
 
 /** convert 0..1 linear value to 0..1 srgb */
 static float linear_to_srgb(float linear) {