Transfer v8 snapshot files as file descriptors to child processes on Posix

content/shell/browser/shell_content_browser_client.cc

Index: content/shell/browser/shell_content_browser_client.cc
diff --git a/content/shell/browser/shell_content_browser_client.cc b/content/shell/browser/shell_content_browser_client.cc
index 9990f5d04742d1540bce0cdbaec42546733bebc7..a73fc9eb20adc67794db671b11429e9357357bdf 100644
--- a/content/shell/browser/shell_content_browser_client.cc
+++ b/content/shell/browser/shell_content_browser_client.cc
@@ -33,6 +33,7 @@
 #include "content/shell/common/shell_messages.h"
 #include "content/shell/common/shell_switches.h"
 #include "content/shell/common/webkit_test_helpers.h"
+#include "gin/public/isolate_holder.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "url/gurl.h"
 
@@ -127,7 +128,12 @@ void ShellContentBrowserClient::SetSwapProcessesForRedirect(bool swap) {
 }
 
 ShellContentBrowserClient::ShellContentBrowserClient()
-    : shell_browser_main_parts_(NULL) {
+    :
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+      v8_natives_fd_(-1),
+      v8_snapshot_fd_(-1),
+#endif  // OS_POSIX && !OS_MACOSX
+      shell_browser_main_parts_(NULL) {
   DCHECK(!g_browser_client);
   g_browser_client = this;
 }
@@ -317,6 +323,28 @@ void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
     const base::CommandLine& command_line,
     int child_process_id,
     FileDescriptorInfo* mappings) {
+#if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+  if (v8_snapshot_fd_.get() == -1 && v8_natives_fd_.get() == -1) {
+    base::FilePath v8_data_path;
+    PathService::Get(gin::IsolateHolder::kV8SnapshotBasePathKey, &v8_data_path);
+    DCHECK(!v8_data_path.empty());
+
+    int file_flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
+    base::FilePath v8_natives_data_path =
+        v8_data_path.AppendASCII(gin::IsolateHolder::kNativesFileName);
+    base::FilePath v8_snapshot_data_path =
+        v8_data_path.AppendASCII(gin::IsolateHolder::kSnapshotFileName);
+    base::File v8_natives_data_file(v8_natives_data_path, file_flags);
+    base::File v8_snapshot_data_file(v8_snapshot_data_path, file_flags);
+    DCHECK(v8_natives_data_file.IsValid());
+    DCHECK(v8_snapshot_data_file.IsValid());
+    v8_natives_fd_.reset(v8_natives_data_file.TakePlatformFile());
+    v8_snapshot_fd_.reset(v8_snapshot_data_file.TakePlatformFile());
+  }
+  mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
+  mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+
 #if defined(OS_ANDROID)
   int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
   base::FilePath pak_file;