Prefer C++ standard headers to their C counterpart (flutter#21091)

We currently use a mix of C standard includes (e.g. limits.h) and their
C++ variants (e.g. climits). This migrates to a consistent style for all
cases where the C++ variants are acceptable, but leaves the C
equivalents in place where they are required, such as in the embedder
API and other headers that may be used from C.

Author: cbracken

common/settings.h

@@ -6,9 +6,9 @@
 #define FLUTTER_COMMON_SETTINGS_H_
 
 #include <fcntl.h>
-#include <stdint.h>
 
 #include <chrono>
+#include <cstdint>
 #include <memory>
 #include <string>
 #include <vector>

examples/glfw/FlutterEmbedderGLFW.cc

@@ -2,10 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <assert.h>
 #include <embedder.h>
 #include <glfw3.h>
 
+#include <cassert>
 #include <chrono>
 #include <iostream>
 

flow/layers/layer_tree.h

@@ -5,8 +5,7 @@
 #ifndef FLUTTER_FLOW_LAYERS_LAYER_TREE_H_
 #define FLUTTER_FLOW_LAYERS_LAYER_TREE_H_
 
-#include <stdint.h>
-
+#include <cstdint>
 #include <memory>
 
 #include "flutter/flow/compositor_context.h"

flow/matrix_decomposition_unittests.cc

@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "flutter/fml/build_config.h"
-
-#if defined(OS_WIN)
 #define _USE_MATH_DEFINES
-#endif
+
 #include <cmath>
 
 #include "flutter/flow/matrix_decomposition.h"

fml/command_line.h

@@ -36,8 +36,7 @@
 #ifndef LIB_FML_COMMAND_LINE_H_
 #define LIB_FML_COMMAND_LINE_H_
 
-#include <stddef.h>
-
+#include <cstddef>
 #include <initializer_list>
 #include <string>
 #include <string_view>

fml/log_settings.cc

@@ -5,9 +5,9 @@
 #include "flutter/fml/log_settings.h"
 
 #include <fcntl.h>
-#include <string.h>
 
 #include <algorithm>
+#include <cstring>
 #include <iostream>
 
 #include "flutter/fml/logging.h"

fml/platform/android/scoped_java_ref.h

@@ -6,7 +6,8 @@
 #define FLUTTER_FML_PLATFORM_ANDROID_SCOPED_JAVA_REF_H_
 
 #include <jni.h>
-#include <stddef.h>
+
+#include <cstddef>
 
 #include "flutter/fml/macros.h"
 

fml/platform/posix/paths_posix.cc

@@ -4,9 +4,10 @@
 
 #include "flutter/fml/paths.h"
 
-#include <limits.h>
 #include <unistd.h>
 
+#include <climits>
+
 #include "flutter/fml/logging.h"
 
 namespace fml {

fml/platform/posix/posix_wrappers_posix.cc

@@ -4,7 +4,7 @@
 
 #include "flutter/fml/posix_wrappers.h"
 
-#include <string.h>
+#include <cstring>
 
 namespace fml {
 

fml/platform/win/file_win.cc

@@ -7,9 +7,10 @@
 #include <Fileapi.h>
 #include <Shlwapi.h>
 #include <fcntl.h>
-#include <limits.h>
 
 #include <algorithm>
+#include <climits>
+#include <cstring>
 #include <sstream>
 
 #include "flutter/fml/build_config.h"