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..ae8e613800925e7841bb1cec75ea2e64b087c299 100644
--- a/base/process/process.h
+++ b/base/process/process.h
@@ -15,6 +15,10 @@
 #include "base/win/scoped_handle.h"
 #endif
 
+#if defined(OS_MACOSX)
+#include "base/process/port_provider_mac.h"
+#endif
+
 namespace base {
 
 // Provides a move-only encapsulation of a process.
@@ -106,6 +110,28 @@ 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|.
+  // Return true if the port_provider can locate a task port for the process and
+  // it

[shrike, 2016/10/31 17:26:04]

Move straggler "it" to the next line?

[lgrey, 2016/10/31 19:22:01]

Done.

+  // 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 +141,7 @@ 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;