Allow backgrounding processes on Mac

content/browser/child_process_launcher.cc

Index: content/browser/child_process_launcher.cc
diff --git a/content/browser/child_process_launcher.cc b/content/browser/child_process_launcher.cc
index 92a3b0e78fe265556e83dffefe4b08d7d26d56ae..76c31cba3a3777e7f3a01d025b15220c04b46b5a 100644
--- a/content/browser/child_process_launcher.cc
+++ b/content/browser/child_process_launcher.cc
@@ -38,8 +38,10 @@
 #include "content/public/common/sandbox_init.h"
 #include "sandbox/win/src/sandbox_types.h"
 #elif defined(OS_MACOSX)
+#include "base/feature_list.h"
 #include "content/browser/bootstrap_sandbox_manager_mac.h"
 #include "content/browser/mach_broker_mac.h"
+#include "content/public/common/content_features.h"
 #include "sandbox/mac/bootstrap_sandbox.h"
 #include "sandbox/mac/pre_exec_delegate.h"
 #elif defined(OS_ANDROID)
@@ -385,7 +387,12 @@ void SetProcessBackgroundedOnLauncherThread(base::Process process,
                                             bool background) {
   DCHECK_CURRENTLY_ON(BrowserThread::PROCESS_LAUNCHER);
   if (process.CanBackgroundProcesses()) {
+#if defined(OS_MACOSX)
+    if (base::FeatureList::IsEnabled(features::kMacBackgroundInactiveTabs))

[shrike, 2016/10/31 17:26:05]

Is this the only place you need to check for the experiment being enabled? I
think UpdateProcessPriority(), for example, can get called from a few different
places and would need this check.

I feel like I remember the experiment check living in SetProcessBackgrounded()
previously, but I guess that won't work with a content feature? If it's possible
to live in SetProcessBackgrounded() (or CanBackgroundProcesses() ) that might be
a better place, so that you have a single chokepoint for calls to background the
process.

 

[lgrey, 2016/10/31 19:22:02]

Moved to CanBackgroundProcesses and moved the feature definition to process. The
only reason I had it in content_features is that's where it seemed like it
belonged if the usage was in content.

+      process.SetProcessBackgrounded(MachBroker::GetInstance(), background);
+#else
     process.SetProcessBackgrounded(background);
+#endif  // defined(OS_MACOSX)
   }
 #if defined(OS_ANDROID)
   SetChildProcessInForeground(process.Handle(), !background);