Allow startup with missing V8 snapshot file.

ash/shell/content_client/shell_content_browser_client.cc

Index: ash/shell/content_client/shell_content_browser_client.cc
diff --git a/ash/shell/content_client/shell_content_browser_client.cc b/ash/shell/content_client/shell_content_browser_client.cc
index 51b0107d5ad9f1b8a532e3793655f9a506b1f193..c5dfbbff08d6a2b8ca5e505722f73de4ec6a3f2c 100644
--- a/ash/shell/content_client/shell_content_browser_client.cc
+++ b/ash/shell/content_client/shell_content_browser_client.cc
@@ -51,8 +51,12 @@ void ShellContentBrowserClient::AppendExtraCommandLineSwitches(
   std::string process_type =
       command_line->GetSwitchValueASCII(switches::kProcessType);
   if (process_type != switches::kZygoteProcess) {
-    command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
-    command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    if (v8_natives_fd_.get() != -1) {

[picksi, 2015/06/02 11:44:37]

"v8_[natives|snapshot]_fd_.get() != -1" appears a lot, is it possible to create
wrapper functions called (something like) natives_exists() & snapshot_exists()?

[Erik Corry Chromium.org, 2015/06/02 14:29:47]

Done.

+      command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
+    }
+    if (v8_snapshot_fd_.get() != -1) {
+      command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    }
   }
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 #endif  // OS_POSIX && !OS_MACOSX
@@ -64,7 +68,7 @@ void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
     int child_process_id,
     content::FileDescriptorInfo* mappings) {
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
-  if (v8_natives_fd_.get() == -1 || v8_snapshot_fd_.get() == -1) {
+  if (v8_natives_fd_.get() == -1) {
     int v8_natives_fd = -1;
     int v8_snapshot_fd = -1;
     if (gin::V8Initializer::OpenV8FilesForChildProcesses(&v8_natives_fd,
@@ -73,7 +77,7 @@ void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
       v8_snapshot_fd_.reset(v8_snapshot_fd);
     }
   }
-  DCHECK(v8_natives_fd_.get() != -1 && v8_snapshot_fd_.get() != -1);
+  DCHECK(v8_natives_fd_.get() != -1);

[rmcilroy, 2015/06/01 14:06:31]

nit - please add a comment saying why its OK if v8_snapshot_fd doesn't get
opened.

[Erik Corry Chromium.org, 2015/06/02 11:18:52]

Done.

   mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
   mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA