Added field trial for enabling AppContainer and a chrome://flags entry.

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 d8689bc71901ec4221f624624125a7596059faa0..334bdefc497c6e8e8af438d9bbd6f8f8a013c1e5 100644
--- a/content/common/sandbox_win.cc
+++ b/content/common/sandbox_win.cc
@@ -13,6 +13,7 @@
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
@@ -569,7 +570,10 @@ void AddAppContainerPolicy(sandbox::TargetPolicy* policy, const wchar_t* sid) {
   if (base::win::GetVersion() >= base::win::VERSION_WIN8) {
     const base::CommandLine& command_line =
         *base::CommandLine::ForCurrentProcess();
-    if (command_line.HasSwitch(switches::kEnableAppContainer)) {
+    std::string appcontainer_trial_name =
+        base::FieldTrialList::FindFullName("EnableAppContainer");
+    if (command_line.HasSwitch(switches::kEnableAppContainer) ||
+        appcontainer_trial_name == "Enabled") {

[Alexei Svitkine (slow), 2015/11/02 17:27:52]

Does this code run in the child process, browser process or both?

I'm asking because I'd like to suggest you to use the new base/feature_list.h
API (which automatically can integrate with FieldTrials without using the
FieldTrial API explicitly), but currently there's a limitation with it that has
an issue with content/ code that runs in the browser process. (I have a CL
fixing this, but it hasn't landed yet).

If this doesn't run in the browser process, then I think it should be fine to
switch to the new API.

       policy->SetLowBox(sid);
     }
   }