Allow backgrounding processes on Mac

base/process/process.h

Index: base/process/process.h
diff --git a/base/process/process.h b/base/process/process.h
index 70c8260193247d079009014f28c5bf72388eca00..5538475863b09f65cba4d7bede6db24b27091f4c 100644
--- a/base/process/process.h
+++ b/base/process/process.h
@@ -15,8 +15,17 @@
 #include "base/win/scoped_handle.h"
 #endif
 
+#if defined(OS_MACOSX)
+#include "base/feature_list.h"
+#include "base/process/port_provider_mac.h"
+#endif
+
 namespace base {
 
+#if defined(OS_MACOSX)
+extern const Feature kMacAllowBackgroundingProcesses;
+#endif
+
 // Provides a move-only encapsulation of a process.
 //
 // This object is not tied to the lifetime of the underlying process: the
@@ -106,6 +115,28 @@ class BASE_EXPORT Process {
   // is not required.
   bool WaitForExitWithTimeout(TimeDelta timeout, int* exit_code);
 
+#if defined(OS_MACOSX)
+  // The Mac needs a Mach port in order to manipulate a process's priority,
+  // and there's no good way to get that from base given the pid. These Mac
+  // variants of the IsProcessBackgrounded and SetProcessBackgrounded API take
+  // a port provider for this reason. See crbug.com/460102
+  //
+  // A process is backgrounded when its task priority is
+  // |TASK_BACKGROUND_APPLICATION|.
+  //
+  // Returns true if the port_provider can locate a task port for the process
+  // and it is backgrounded. If port_provider is null, returns false.
+  bool IsProcessBackgrounded(PortProvider* port_provider) const;
+
+  // Set the process as backgrounded. If value is
+  // true, the priority of the associated task will be set to
+  // TASK_BACKGROUND_APPLICATION. If value is false, the
+  // priority of the process will be set to TASK_FOREGROUND_APPLICATION.
+  //
+  // Returns true if the priority was changed, false otherwise. If
+  // |port_provider| is null, this is a no-op and it returns false.
+  bool SetProcessBackgrounded(PortProvider* port_provider, bool value);
+#else
   // A process is backgrounded when it's priority is lower than normal.
   // Return true if this process is backgrounded, false otherwise.
   bool IsProcessBackgrounded() const;
@@ -115,7 +146,7 @@ class BASE_EXPORT Process {
   // will be made "normal" - equivalent to default process priority.
   // Returns true if the priority was changed, false otherwise.
   bool SetProcessBackgrounded(bool value);
-
+#endif  // defined(OS_MACOSX)
   // Returns an integer representing the priority of a process. The meaning
   // of this value is OS dependent.
   int GetPriority() const;