re-precate SkMatrix44::SkMatrix44()

It's been driving me nuts that I can't just write `SkMatrix44 m;`,
and I often don't care whether it's initialized or not.  The default
identity constructor would be nice to use, but it's deprecated.

By tagging this constructor deprecated, we're only hurting ourselves;
our big clients disable warnings about deprecated routines and use it
freely.

A quick tally in Skia shows we mostly use the uninitialized constructor,
but sometimes the identity constructor, and there is a spread of all
three in Chromium.  So I've left the two explicit calls available.

I switched a bunch of calls in Skia to use the less verbose constructor
where it was clear that it didn't matter if the matrix was initialized.
Literally zero of the kUninitialized constructor calls looked important
for performance, so the only place I've kept is its lone unit test.

A few places read clearer with an explicit "identity" to read.

Change-Id: I0573cb6201f5a36f3b43070fb111f7d9af92736f
Reviewed-on: https://skia-review.googlesource.com/c/159480
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index 2e1562b..681c441 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -115,13 +115,13 @@
 }
 
 sk_sp<SkColorSpace> SkColorSpace::MakeRGB(RenderTargetGamma gamma, Gamut gamut) {
-    SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 toXYZD50;
     to_xyz_d50(&toXYZD50, gamut);
     return SkColorSpace::MakeRGB(gamma, toXYZD50);
 }
 
 sk_sp<SkColorSpace> SkColorSpace::MakeRGB(const SkColorSpaceTransferFn& coeffs, Gamut gamut) {
-    SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 toXYZD50;
     to_xyz_d50(&toXYZD50, gamut);
     return SkColorSpace::MakeRGB(coeffs, toXYZD50);
 }
@@ -129,7 +129,7 @@
 class SkColorSpaceSingletonFactory {
 public:
     static SkColorSpace* Make(SkGammaNamed gamma, const float to_xyz[9]) {
-        SkMatrix44 m44(SkMatrix44::kUninitialized_Constructor);
+        SkMatrix44 m44;
         m44.set3x3RowMajorf(to_xyz);
         (void)m44.getType();  // Force typemask to be computed to avoid races.
         return new SkColorSpace(gamma, nullptr, m44);
@@ -197,7 +197,7 @@
 
 const SkMatrix44* SkColorSpace::toXYZD50() const {
     fToXZYD50_4x4_Once([this] {
-        fToXYZD50_4x4.reset(new SkMatrix44(SkMatrix44::kUninitialized_Constructor));
+        fToXYZD50_4x4.reset(new SkMatrix44);
         fToXYZD50_4x4->set3x3RowMajorf(fToXYZD50_3x3);
     });
     return fToXYZD50_4x4.get();
@@ -230,7 +230,7 @@
     if (this->gammaIsLinear()) {
         return sk_ref_sp(const_cast<SkColorSpace*>(this));
     }
-    SkMatrix44 m44(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 m44;
     this->toXYZD50(&m44);
     return SkColorSpace::MakeRGB(kLinear_SkGammaNamed, m44);
 }
@@ -239,16 +239,16 @@
     if (this->gammaCloseToSRGB()) {
         return sk_ref_sp(const_cast<SkColorSpace*>(this));
     }
-    SkMatrix44 m44(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 m44;
     this->toXYZD50(&m44);
     return SkColorSpace::MakeRGB(kSRGB_SkGammaNamed, m44);
 }
 
 sk_sp<SkColorSpace> SkColorSpace::makeColorSpin() const {
-    SkMatrix44 spin(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 spin;
     spin.set3x3(0, 1, 0, 0, 0, 1, 1, 0, 0);
 
-    SkMatrix44 m44(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 m44;
     this->toXYZD50(&m44);
     spin.postConcat(m44);
 
@@ -279,7 +279,7 @@
     }
 
     // TODO: can we save this work and skip lazily inverting the matrix later?
-    SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 toXYZD50;
     toXYZD50.set3x3RowMajorf(&profile.toXYZD50.vals[0][0]);
     if (!toXYZD50.invert(nullptr)) {
         return nullptr;
@@ -396,7 +396,7 @@
                         ColorSpaceHeader::Pack(k0_Version, 0, gammaNamed,
                                                 ColorSpaceHeader::kMatrix_Flag);
                 memory = SkTAddOffset<void>(memory, sizeof(ColorSpaceHeader));
-                SkMatrix44 m44{SkMatrix44::kUninitialized_Constructor};
+                SkMatrix44 m44;
                 this->toXYZD50(&m44);
                 m44.as3x4RowMajorf((float*) memory);
             }
@@ -421,7 +421,7 @@
                 *(((float*) memory) + 6) = transferFn.fG;
                 memory = SkTAddOffset<void>(memory, 7 * sizeof(float));
 
-                SkMatrix44 m44{SkMatrix44::kUninitialized_Constructor};
+                SkMatrix44 m44;
                 this->toXYZD50(&m44);
                 m44.as3x4RowMajorf((float*) memory);
             }
@@ -469,7 +469,7 @@
                 return nullptr;
             }
 
-            SkMatrix44 toXYZ(SkMatrix44::kUninitialized_Constructor);
+            SkMatrix44 toXYZ;
             toXYZ.set3x4RowMajorf((const float*) data);
             return SkColorSpace::MakeRGB((SkGammaNamed) header.fGammaNamed, toXYZ);
         }
@@ -497,7 +497,7 @@
             transferFn.fG = *(((const float*) data) + 6);
             data = SkTAddOffset<const void>(data, 7 * sizeof(float));
 
-            SkMatrix44 toXYZ(SkMatrix44::kUninitialized_Constructor);
+            SkMatrix44 toXYZ;
             toXYZ.set3x4RowMajorf((const float*) data);
             return SkColorSpace::MakeRGB(transferFn, toXYZ);
         }
diff --git a/src/core/SkMatrix44.cpp b/src/core/SkMatrix44.cpp
index a79b703..1b08987 100644
--- a/src/core/SkMatrix44.cpp
+++ b/src/core/SkMatrix44.cpp
@@ -496,7 +496,7 @@
         return true;
     }
 
-    SkMatrix44 tmp(kUninitialized_Constructor);
+    SkMatrix44 tmp;
     // Use storage if it's available and distinct from this matrix.
     SkMatrix44* inverse = (storage && storage != this) ? storage : &tmp;
     if (this->isScaleTranslate()) {
diff --git a/src/gpu/effects/GrYUVtoRGBEffect.cpp b/src/gpu/effects/GrYUVtoRGBEffect.cpp
index c1b77b4..f13cff4 100644
--- a/src/gpu/effects/GrYUVtoRGBEffect.cpp
+++ b/src/gpu/effects/GrYUVtoRGBEffect.cpp
@@ -44,7 +44,7 @@
              (vProxy->width() != yProxy->width()) || (vProxy->height() != yProxy->height()))
                     ? GrSamplerState::Filter::kBilerp
                     : GrSamplerState::Filter::kNearest;
-    SkMatrix44 mat(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 mat;
     switch (colorSpace) {
         case kJPEG_SkYUVColorSpace:
             mat.setColMajorf(kJPEGConversionMatrix);
diff --git a/src/gpu/effects/GrYUVtoRGBEffect.fp b/src/gpu/effects/GrYUVtoRGBEffect.fp
index 453800d..cff255e 100644
--- a/src/gpu/effects/GrYUVtoRGBEffect.fp
+++ b/src/gpu/effects/GrYUVtoRGBEffect.fp
@@ -88,7 +88,7 @@
              (vProxy->height() != yProxy->height())) ?
             GrSamplerState::Filter::kBilerp :
             GrSamplerState::Filter::kNearest;
-        SkMatrix44 mat(SkMatrix44::kUninitialized_Constructor);
+        SkMatrix44 mat;
         switch (colorSpace) {
             case kJPEG_SkYUVColorSpace:
                 mat.setColMajorf(kJPEGConversionMatrix);
diff --git a/src/images/SkImageEncoderFns.h b/src/images/SkImageEncoderFns.h
index cd99729..6cde0cb 100644
--- a/src/images/SkImageEncoderFns.h
+++ b/src/images/SkImageEncoderFns.h
@@ -392,7 +392,7 @@
     }
 
     SkColorSpaceTransferFn fn;
-    SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor);
+    SkMatrix44 toXYZD50;
     if (cs->isNumericalTransferFn(&fn) && cs->toXYZD50(&toXYZD50)) {
         return SkICC::WriteToICC(fn, toXYZD50);
     }