Revert "Increase accuracy of float -> fixed in ICC code"

This reverts commit ef8dda227b55445de090cfc5c59fb633f8a1763d.

Reason for revert: This is breaking WebKit layout tests on linux and blocking the autoroller. Probably just needs a rebase. See:
https://storage.googleapis.com/chromium-layout-test-archives/linux_trusty_blink_rel/20229/layout-test-results/results.html

Original change's description:
> Increase accuracy of float -> fixed in ICC code
> 
> Add a comment to SkFixed explaining the accuracy issues of the macros.
> 
> Bug: skia:
> Change-Id: Ibfecb16821fefe87822cc3acd1cf8498df10a492
> Reviewed-on: https://skia-review.googlesource.com/85742
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>

TBR=mtklein@chromium.org,brianosman@google.com,reed@google.com

Change-Id: I354327767bd59a6104b1431b053721c3102719be
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/86281
Reviewed-by: Eric Karl <ericrk@chromium.org>
Commit-Queue: Eric Karl <ericrk@chromium.org>

1 files changed, 10 insertions, 18 deletions

diff --git a/src/core/SkICC.cpp b/src/core/SkICC.cpp
index cfc66e1238..128bce368d 100644
--- a/src/core/SkICC.cpp
+++ b/src/core/SkICC.cpp
@@ -281,33 +281,25 @@ static constexpr uint32_t kICCTagTable[3 * kICCNumEntries] {
     SkEndian_SwapBE32(kTAG_cprt_Bytes),
 };
 
-// This is like SkFloatToFixed, but rounds to nearest, preserving as much accuracy as possible
-// when going float -> fixed -> float (it has the same accuracy when going fixed -> float -> fixed).
-// The use of double is necessary to accomodate the full potential 32-bit mantissa of the 16.16
-// SkFixed value, and so avoiding rounding problems with float. Also, see the comment in SkFixed.h.
-static SkFixed float_round_to_fixed(float x) {
-    return sk_float_saturate2int((float)floor((double)x * SK_Fixed1 + 0.5));
-}
-
 static void write_xyz_tag(uint32_t* ptr, const SkMatrix44& toXYZ, int col) {
     ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace);
     ptr[1] = 0;
-    ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZ.getFloat(0, col)));
-    ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZ.getFloat(1, col)));
-    ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZ.getFloat(2, col)));
+    ptr[2] = SkEndian_SwapBE32(SkFloatToFixed(toXYZ.getFloat(0, col)));
+    ptr[3] = SkEndian_SwapBE32(SkFloatToFixed(toXYZ.getFloat(1, col)));
+    ptr[4] = SkEndian_SwapBE32(SkFloatToFixed(toXYZ.getFloat(2, col)));
 }
 
 static void write_trc_tag(uint32_t* ptr, const SkColorSpaceTransferFn& fn) {
     ptr[0] = SkEndian_SwapBE32(kTAG_ParaCurveType);
     ptr[1] = 0;
     ptr[2] = (uint32_t) (SkEndian_SwapBE16(kGABCDEF_ParaCurveType));
-    ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(fn.fG));
-    ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.fA));
-    ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.fB));
-    ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.fC));
-    ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.fD));
-    ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.fE));
-    ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.fF));
+    ptr[3] = SkEndian_SwapBE32(SkFloatToFixed(fn.fG));
+    ptr[4] = SkEndian_SwapBE32(SkFloatToFixed(fn.fA));
+    ptr[5] = SkEndian_SwapBE32(SkFloatToFixed(fn.fB));
+    ptr[6] = SkEndian_SwapBE32(SkFloatToFixed(fn.fC));
+    ptr[7] = SkEndian_SwapBE32(SkFloatToFixed(fn.fD));
+    ptr[8] = SkEndian_SwapBE32(SkFloatToFixed(fn.fE));
+    ptr[9] = SkEndian_SwapBE32(SkFloatToFixed(fn.fF));
 }
 
 static bool is_3x3(const SkMatrix44& toXYZD50) {