chromeos: Add asynchronous version of GetSystemSalt()

The old synchronous implementation is renamed to GetSystemSaltSync().
The old implementation is marked as deprecated and all users will switch to GetSystemSalt() soon.

BUG=141009
TEST=build
R=satorux@chromium.org
TBR=bbudge@chromium.org for c/b/renderer_host/pepper, benwells@chromium.org for c/b/extensions/api/music_manager_private

Review URL: https://codereview.chromium.org/26697005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227874 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 25 insertions, 5 deletions

diff --git a/chromeos/cryptohome/cryptohome_library.cc b/chromeos/cryptohome/cryptohome_library.cc
index 29745ca..e07dd60 100644
--- a/chromeos/cryptohome/cryptohome_library.cc
+++ b/chromeos/cryptohome/cryptohome_library.cc
@@ -7,7 +7,9 @@
 #include <map>
 
 #include "base/bind.h"
+#include "base/location.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/sys_info.h"
@@ -32,7 +34,13 @@ class CryptohomeLibraryImpl : public CryptohomeLibrary {
   virtual ~CryptohomeLibraryImpl() {
   }
 
-  virtual std::string GetSystemSalt() OVERRIDE {
+  virtual void GetSystemSalt(const GetSystemSaltCallback& callback) OVERRIDE {
+    // TODO(hashimoto): Stop using GetSystemSaltSynt(). crbug.com/141009
+    base::MessageLoopProxy::current()->PostTask(
+        FROM_HERE, base::Bind(callback, GetSystemSaltSync()));
+  }
+
+  virtual std::string GetSystemSaltSync() OVERRIDE {
     LoadSystemSalt();  // no-op if it's already loaded.
     return system_salt_;
   }
@@ -65,7 +73,12 @@ class CryptohomeLibraryStubImpl : public CryptohomeLibrary {
   CryptohomeLibraryStubImpl() {}
   virtual ~CryptohomeLibraryStubImpl() {}
 
-  virtual std::string GetSystemSalt() OVERRIDE {
+  virtual void GetSystemSalt(const GetSystemSaltCallback& callback) OVERRIDE {
+    base::MessageLoopProxy::current()->PostTask(
+        FROM_HERE, base::Bind(callback, kStubSystemSalt));
+  }
+
+  virtual std::string GetSystemSaltSync() OVERRIDE {
     return kStubSystemSalt;
   }
 
diff --git a/chromeos/cryptohome/cryptohome_library.h b/chromeos/cryptohome/cryptohome_library.h
index b427ae2..9b33bd5 100644
--- a/chromeos/cryptohome/cryptohome_library.h
+++ b/chromeos/cryptohome/cryptohome_library.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "chromeos/chromeos_export.h"
 
 namespace chromeos {
@@ -16,6 +17,9 @@ namespace chromeos {
 // APIs.
 class CHROMEOS_EXPORT CryptohomeLibrary {
  public:
+  typedef base::Callback<void(const std::string& system_salt)>
+      GetSystemSaltCallback;
+
   // Manage an explicitly initialized global instance.
   static void Initialize();
   static bool IsInitialized();
@@ -36,9 +40,12 @@ class CHROMEOS_EXPORT CryptohomeLibrary {
   // Returns system hash in hex encoded ascii format. Note: this may return
   // an empty string (e.g. if cryptohome is not running). It is up to the
   // calling function to try again after a delay if desired.
-  //
-  // TODO(hashimoto): Make it asynchronous. crbug.com/141009.
-  virtual std::string GetSystemSalt() = 0;
+  virtual void GetSystemSalt(const GetSystemSaltCallback& callback) = 0;
+
+  // Synchronous version of GetSystemSalt().
+  // Blocks the UI thread until the Cryptohome service returns the result.
+  // DEPRECATED: DO NOT USE.
+  virtual std::string GetSystemSaltSync() = 0;
 
   // Returns system hash in hex encoded ascii format, cached by a prior call
   // to GetSystemSalt(). Note: this may return an empty string (e.g. if