Allow startup with missing V8 snapshot file.

content/shell/browser/shell_content_browser_client.h

Index: content/shell/browser/shell_content_browser_client.h
diff --git a/content/shell/browser/shell_content_browser_client.h b/content/shell/browser/shell_content_browser_client.h
index 0dc59b202254a2469bfb80410221ba271d6e20db..fe843a67acbb80880126b3e3d3fb787e9fb5a60f 100644
--- a/content/shell/browser/shell_content_browser_client.h
+++ b/content/shell/browser/shell_content_browser_client.h
@@ -46,6 +46,8 @@ class ShellContentBrowserClient : public ContentBrowserClient {
   bool IsHandledURL(const GURL& url) override;
   void AppendExtraCommandLineSwitches(base::CommandLine* command_line,
                                       int child_process_id) override;
+  void AppendMappedFileCommandLineSwitches(
+      base::CommandLine* command_line) override;
   void OverrideWebkitPrefs(RenderViewHost* render_view_host,
                            WebPreferences* prefs) override;
   void ResourceDispatcherHostCreated() override;
@@ -106,6 +108,8 @@ class ShellContentBrowserClient : public ContentBrowserClient {
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   base::ScopedFD v8_natives_fd_;
   base::ScopedFD v8_snapshot_fd_;
+  bool natives_fd_exists() { return v8_natives_fd_ != -1; }
+  bool snapshot_fd_exists() { return v8_snapshot_fd_ != -1; }
 #endif
 
   base::Closure select_client_certificate_callback_;