Define _USE_MATH_DEFINES on Windows where needed (#21166)

flow/BUILD.gn

@@ -174,6 +174,14 @@ if (enable_unittests) {
       "//third_party/skia",
     ]
 
+    if (!defined(defines)) {
+      defines = []
+    }
+    if (is_win) {
+      # Required for M_PI and others.
+      defines += [ "_USE_MATH_DEFINES" ]
+    }
+
     if (is_fuchsia && flutter_enable_legacy_fuchsia_embedder) {
       sources += [ "layers/fuchsia_layer_unittests.cc" ]
 

flow/matrix_decomposition_unittests.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define _USE_MATH_DEFINES
-
 #include "flutter/flow/matrix_decomposition.h"
 
 #include <cmath>

lib/ui/BUILD.gn

@@ -129,8 +129,15 @@ source_set("ui") {
     "//third_party/skia",
   ]
 
+  if (!defined(defines)) {
+    defines = []
+  }
   if (flutter_enable_skshaper) {
-    defines = [ "FLUTTER_ENABLE_SKSHAPER" ]
+    defines += [ "FLUTTER_ENABLE_SKSHAPER" ]
+  }
+  if (is_win) {
+    # Required for M_PI and others.
+    defines += [ "_USE_MATH_DEFINES" ]
   }
 
   if (is_fuchsia && flutter_enable_legacy_fuchsia_embedder) {

lib/ui/painting/canvas.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define _USE_MATH_DEFINES
-
 #include "flutter/lib/ui/painting/canvas.h"
 
 #include <cmath>

lib/ui/painting/gradient.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define _USE_MATH_DEFINES
-
 #include "flutter/lib/ui/painting/gradient.h"
 
 #include "third_party/tonic/converter/dart_converter.h"

lib/ui/painting/path.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define _USE_MATH_DEFINES
-
 #include "flutter/lib/ui/painting/path.h"
 
 #include <cmath>

lib/ui/painting/path_measure.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define _USE_MATH_DEFINES
-
 #include "flutter/lib/ui/painting/path_measure.h"
 
 #include <cmath>