Add IsSandboxed() function to seatbelt wrapper.

sandbox/mac/seatbelt.h

Index: sandbox/mac/seatbelt.h
diff --git a/sandbox/mac/seatbelt.h b/sandbox/mac/seatbelt.h
index 2a5db08e4b6f3a38b9c19eac383fb62cab6a52b5..f19715902f0f526efe811500b1868e86e204961e 100644
--- a/sandbox/mac/seatbelt.h
+++ b/sandbox/mac/seatbelt.h
@@ -17,15 +17,28 @@ namespace sandbox {
 // This class wraps the functions in deprecation warning supressions.
 class SEATBELT_EXPORT Seatbelt {
  public:
+  // Initializes the specified sandbox profile. Returns 0 on success, else -1
+  // and |errorbuf| is populated. |errorbuf| is allocated by the API and must be
+  // freed with FreeError().
   static int Init(const char* profile, uint64_t flags, char** errorbuf);
 
+  // Initializes the specified sandbox profile and passes the parameters to the
+  // |profile|. |parameters| is a null terminated list containing key,value
+  // pairs in sequence. [key1,val1,key2,val2,nullptr]. |errorbuf| is allocated
+  // by the API and is set to a string description of the error. |errorbuf| must
+  // be freed with FreeError(). This function eturns 0 on success, else -1 and
+  // |errorbuf| is populated.
   static int InitWithParams(const char* profile,
                             uint64_t flags,
                             const char* const parameters[],
                             char** errorbuf);
 
+  // Frees the |errorbuf| allocated and set by InitWithParams.
   static void FreeError(char* errorbuf);
 
+  // Returns whether or not the process is currently sandboxed.
+  static bool IsSandboxed();
+
   static const char* kProfileNoInternet;
 
   static const char* kProfileNoNetwork;