Support DirectWrite with sandbox on

content/common/sandbox_win.cc

Index: content/common/sandbox_win.cc
diff --git a/content/common/sandbox_win.cc b/content/common/sandbox_win.cc
index aea586054e51329e97627abc203ac3cfdb7f2b06..9876571ebb2a3d6a1f87e75c3dbb77b851d9878e 100644
--- a/content/common/sandbox_win.cc
+++ b/content/common/sandbox_win.cc
@@ -571,6 +571,16 @@ bool InitTargetServices(sandbox::TargetServices* target_services) {
   return sandbox::SBOX_ALL_OK == result;
 }
 
+bool ShouldUseDirectWrite() {
+  // If the flag is currently on, and we're on Win7 or above, we enable
+  // DirectWrite. Skia does not require the additions to DirectWrite
+  // in QFE 2670838, so a Win7 check is sufficient. We don't not currently
+  // attempt to support Vista, where SP2 and the Platform Update are required.
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  return command_line.HasSwitch(switches::kEnableDirectWrite) &&
+         base::win::GetVersion() >= base::win::VERSION_WIN7;
+}
+
 base::ProcessHandle StartSandboxedProcess(
     SandboxedProcessLauncherDelegate* delegate,
     CommandLine* cmd_line) {
@@ -642,6 +652,16 @@ base::ProcessHandle StartSandboxedProcess(
     // this subprocess. See
     // http://code.google.com/p/chromium/issues/detail?id=25580
     cmd_line->AppendSwitchASCII("ignored", " --type=renderer ");
+  } else if (ShouldUseDirectWrite()) {

[jam, 2014/03/25 22:57:26]

nit: it would be clearer to have if (type_str == renderer) {} else {} instead of
this 

[scottmg, 2014/03/25 23:38:18]

Done.

+    AddDirectory(base::DIR_WINDOWS_FONTS,
+                 NULL,
+                 true,
+                 sandbox::TargetPolicy::FILES_ALLOW_READONLY,
+                 policy);
+    // We do not automatically propagate this from the browser command line,
+    // and instead only add it when we're actually setting up the sandbox to
+    // work with DirectWrite.
+    cmd_line->AppendSwitch(switches::kEnableDirectWrite);
   }
 
   sandbox::ResultCode result;