Moved logic for mapping child process FDs for ICU and V8 into child_process_launcher.cc

gin/v8_initializer.h

Index: gin/v8_initializer.h
diff --git a/gin/v8_initializer.h b/gin/v8_initializer.h
index 1e05fd038c8a4696358bfd0eb4a094a3ab95d7c9..a4cde2fc2d35863bb39e46c38de4158e1e3fcbf2 100644
--- a/gin/v8_initializer.h
+++ b/gin/v8_initializer.h
@@ -6,6 +6,7 @@
 #define GIN_V8_INITIALIZER_H_
 
 #include "base/files/file.h"
+#include "base/files/memory_mapped_file.h"
 #include "gin/array_buffer.h"
 #include "gin/gin_export.h"
 #include "gin/public/isolate_holder.h"
@@ -50,12 +51,17 @@ class GIN_EXPORT V8Initializer {
   // so that it will not return if natives cannot be loaded.
   static void LoadV8Natives();
 
-  // Opens the V8 snapshot data files and returns open file descriptors to these
-  // files in |natives_fd_out| and |snapshot_fd_out|, which can be passed to
-  // child processes.
-  static bool OpenV8FilesForChildProcesses(base::PlatformFile* natives_fd_out,
-                                           base::PlatformFile* snapshot_fd_out)
-      WARN_UNUSED_RESULT;
+  // Opens (unless already cached) and returns the V8 natives file.
+  // Use with LoadV8NativesFromFD().
+  // Asserts if the file does not exist.
+  static base::PlatformFile OpenNativesFileForChildProcesses(
+      base::MemoryMappedFile::Region* region_out);
+
+  // Opens (unless already cached) and returns the V8 snapshot file.
+  // Use with LoadV8SnapshotFromFD().
+  // Will return -1 if the file does not exist.
+  static base::PlatformFile OpenSnapshotFileForChildProcesses(
+      base::MemoryMappedFile::Region* region_out);
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 };