PNaCl on-demand installs: Make a separate async IPC to check if PNaCl is installed

components/nacl/common/pnacl_types.h

Index: components/nacl/common/pnacl_types.h
diff --git a/components/nacl/common/pnacl_types.h b/components/nacl/common/pnacl_types.h
index 802319bd7110934b0e9acba263d8a241d81ed45c..3fc405a980da7186191c61c14c7a787f3c8ab5c0 100644
--- a/components/nacl/common/pnacl_types.h
+++ b/components/nacl/common/pnacl_types.h
@@ -9,6 +9,7 @@
 // nacl_types is built into nacl_helper in addition to chrome, and we don't
 // want to pull src/url/ into there, since it would be unnecessary bloat.
 
+#include "base/basictypes.h"
 #include "base/time/time.h"
 #include "url/gurl.h"
 
@@ -28,6 +29,20 @@ struct PnaclCacheInfo {
   std::string etag;
 };
 
+// Progress information for PNaCl on-demand installs.
+struct PnaclInstallProgress {
+  int64 current;
+  int64 total_size;
+
+  // Returns an instance of PnaclInstallProgress where the
+  // total is marked as unknown.
+  static PnaclInstallProgress Unknown();
+
+  // Returns true if the given instance of PnaclInstallProgress has
+  // an unknown total.
+  static bool progress_known(const PnaclInstallProgress& p);
+};
+
 }  // namespace nacl
 
 #endif  // COMPONENTS_NACL_COMMON_PNACL_TYPES_H_