PlatformKeysService: Process state accessing operations sequentially.

To prevent concurrent updates and reading old state, operations have to executed in sequence if they read or modify an extension's StateStore.

This change is not affecting/modifying the crypto operations but only changes the processing order of the operations.

BUG=450167

Review URL: https://codereview.chromium.org/892103003

Cr-Commit-Position: refs/heads/master@{#316411}

chrome/browser/chromeos/platform_keys/platform_keys_service.h

@@ -5,11 +5,13 @@
 #ifndef CHROME_BROWSER_CHROMEOS_PLATFORM_KEYS_PLATFORM_KEYS_SERVICE_H_
 #define CHROME_BROWSER_CHROMEOS_PLATFORM_KEYS_PLATFORM_KEYS_SERVICE_H_
 
+#include <queue>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
+#include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/chromeos/platform_keys/platform_keys.h"
@@ -134,20 +136,19 @@ class PlatformKeysService : public KeyedService {
   using GetPlatformKeysCallback =
       base::Callback<void(scoped_ptr<base::ListValue> platform_keys)>;
 
-  // Registers the given public key as newly generated key, which is allowed to
-  // be used for signing for a single time. Afterwards, calls |callback|. If
-  // registration was successful, passes |true| otherwise |false| to the
-  // callback.
-  void RegisterPublicKey(const std::string& extension_id,
-                         const std::string& public_key_spki_der,
-                         const base::Closure& callback);
-
-  // Gets the current validity of the given public key by reading StateStore.
-  // Invalidates the key if it was found to be valid. Finally, calls |callback|
-  // with the old validity.
-  void ReadValidityAndInvalidateKey(const std::string& extension_id,
-                                    const std::string& public_key_spki_der,
-                                    const base::Callback<void(bool)>& callback);
+  class Task;
+  class SignTask;
+  class PermissionUpdateTask;
+
+  // Starts |task| eventually. To ensure that at most one |Task| is running at a
+  // time, it queues |task| for later execution if necessary.
+  void StartOrQueueTask(scoped_ptr<Task> task);
+
+  // Must be called after |task| is done. |task| will be invalid after this
+  // call. This must not be called for any but the task that ran last. If any
+  // other tasks are queued (see StartOrQueueTask()), it will start the next
+  // one.
+  void TaskFinished(Task* task);
 
   // Reads the list of public keys currently registered for |extension_id| from
   // StateStore. Calls |callback| with the read list, or a new empty list if
@@ -165,10 +166,18 @@ class PlatformKeysService : public KeyedService {
   // for the given extension. If any error occurs during key generation or
   // registration, calls |callback| with an error. Otherwise, on success, calls
   // |callback| with the public key.
-  void GenerateRSAKeyCallback(const std::string& extension_id,
-                              const GenerateKeyCallback& callback,
+  void GeneratedKey(const std::string& extension_id,
+                    const GenerateKeyCallback& callback,
+                    const std::string& public_key_spki_der,
+                    const std::string& error_message);
+
+  // Callback used by |GeneratedKey|.
+  // |public_key_spki_der| will contain the X.509 Subject Public Key Info  of
+  // the generated key in DER encoding. |task| points to the finished |Task|
+  // object.
+  void RegisteredGeneratedKey(const GenerateKeyCallback& callback,
                               const std::string& public_key_spki_der,
-                              const std::string& error_message);
+                              Task* task);
 
   // Calback used by |SelectClientCertificates|.
   // If the certificate request could be processed successfully, |matches| will
@@ -181,23 +190,6 @@ class PlatformKeysService : public KeyedService {
       scoped_ptr<net::CertificateList> matches,
       const std::string& error_message);
 
-  // Callback used by |RegisterPublicKey|.
-  // Updates the old |platform_keys| read from the StateStore and writes the
-  // updated value back to the StateStore.
-  void RegisterPublicKeyGotPlatformKeys(
-      const std::string& extension_id,
-      const std::string& public_key_spki_der,
-      const base::Closure& callback,
-      scoped_ptr<base::ListValue> platform_keys);
-
-  // Callback used by |ReadValidityAndInvalidateKey|.
-  // Invalidates the given public key so that future signing is prohibited and
-  // calls |callback| with the old validity.
-  void InvalidateKey(const std::string& extension_id,
-                     const std::string& public_key_spki_der,
-                     const base::Callback<void(bool)>& callback,
-                     scoped_ptr<base::ListValue> platform_keys);
-
   // Callback used by |GetPlatformKeysOfExtension|.
   // Is called with |value| set to the PlatformKeys value read from the
   // StateStore, which it forwards to |callback|. On error, calls |callback|
@@ -209,6 +201,7 @@ class PlatformKeysService : public KeyedService {
   content::BrowserContext* browser_context_;
   extensions::StateStore* state_store_;
   bool permission_check_enabled_ = true;
+  std::queue<linked_ptr<Task>> tasks_;
   base::WeakPtrFactory<PlatformKeysService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformKeysService);