Make ServerBoundCertStore interface async, move SQLiteServerBoundCertStore load onto DB thread.

chrome/browser/net/sqlite_server_bound_cert_store.cc

Index: chrome/browser/net/sqlite_server_bound_cert_store.cc
diff --git a/chrome/browser/net/sqlite_server_bound_cert_store.cc b/chrome/browser/net/sqlite_server_bound_cert_store.cc
index fb6ab57c3d61c8791ab7fc75de3cd50ec3719f72..2d7822df67241f294b08297dc08bd29c22795f83 100644
--- a/chrome/browser/net/sqlite_server_bound_cert_store.cc
+++ b/chrome/browser/net/sqlite_server_bound_cert_store.cc
@@ -41,9 +41,8 @@ class SQLiteServerBoundCertStore::Backend
         clear_on_exit_policy_(clear_on_exit_policy) {
   }
 
-  // Creates or load the SQLite database.
-  bool Load(
-      std::vector<net::DefaultServerBoundCertStore::ServerBoundCert*>* certs);
+  // Creates or loads the SQLite database.
+  void Load(const LoadedCallback& loaded_callback);
 
   // Batch a server bound cert addition.
   void AddServerBoundCert(
@@ -63,6 +62,9 @@ class SQLiteServerBoundCertStore::Backend
   void SetForceKeepSessionState();
 
  private:
+  bool LoadOnDBThread(
+      std::vector<net::DefaultServerBoundCertStore::ServerBoundCert*>* certs);
+
   friend class base::RefCountedThreadSafe<SQLiteServerBoundCertStore::Backend>;
 
   // You should call Close() before destructing this object.
@@ -155,15 +157,27 @@ bool InitTable(sql::Connection* db) {
 
 }  // namespace
 
-bool SQLiteServerBoundCertStore::Backend::Load(
-    std::vector<net::DefaultServerBoundCertStore::ServerBoundCert*>* certs) {
+void SQLiteServerBoundCertStore::Backend::Load(
+    const LoadedCallback& loaded_callback) {
   // This function should be called only once per instance.
   DCHECK(!db_.get());
 
-  // TODO(paivanof@gmail.com): We do a lot of disk access in this function,
-  // thus we do an exception to allow IO on the UI thread. This code will be
-  // moved to the DB thread as part of http://crbug.com/89665.
-  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  scoped_ptr<ScopedVector<net::DefaultServerBoundCertStore::ServerBoundCert> >
+      certs(new ScopedVector<net::DefaultServerBoundCertStore::ServerBoundCert>(
+          ));
+  BrowserThread::PostTaskAndReply(
+      BrowserThread::DB, FROM_HERE,
+      base::Bind(base::IgnoreResult(&Backend::LoadOnDBThread), this,
+                 &certs->get()),
+      base::Bind(loaded_callback, base::Passed(&certs)));
+}
+
+bool SQLiteServerBoundCertStore::Backend::LoadOnDBThread(

[erikwright (departed), 2013/01/04 19:20:10]

why keep the bool exit code?

Also, consider simplifying by making the callback a parameter of LoadOnDBThread.

Then you just bind in the callback, and LoadOnDBThread, upon completion, just
re-binds the callback to the result ScopedVector and posts it back to the IO
thread.

[mattm, 2013/01/08 04:53:21]

removed.
Well, because of all the early exits in LoadOnDBThread, I'd want to make a
wrapper method to do the actual posting instead of directly from LoadOnDBThread.
In that case I'm not sure it's really simpler, but I changed it.

[erikwright (departed), 2013/01/10 22:03:30]

I see your point. I don't mind either way.

+    std::vector<net::DefaultServerBoundCertStore::ServerBoundCert*>* certs) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+
+  // This method should be called only once per instance.
+  DCHECK(!db_.get());
 
   base::TimeTicks start = base::TimeTicks::Now();
 
@@ -218,11 +232,14 @@ bool SQLiteServerBoundCertStore::Backend::Load(
   }
 
   UMA_HISTOGRAM_COUNTS_10000("DomainBoundCerts.DBLoadedCount", certs->size());
+  base::TimeDelta load_time = base::TimeTicks::Now() - start;
   UMA_HISTOGRAM_CUSTOM_TIMES("DomainBoundCerts.DBLoadTime",
-                             base::TimeTicks::Now() - start,
+                             load_time,
                              base::TimeDelta::FromMilliseconds(1),
                              base::TimeDelta::FromMinutes(1),
                              50);
+  DVLOG(1) << "loaded " << certs->size() << " in " << load_time.InMilliseconds()
+           << " ms";
   return true;
 }
 
@@ -544,9 +561,9 @@ SQLiteServerBoundCertStore::SQLiteServerBoundCertStore(
     : backend_(new Backend(path, clear_on_exit_policy)) {
 }
 
-bool SQLiteServerBoundCertStore::Load(
-    std::vector<net::DefaultServerBoundCertStore::ServerBoundCert*>* certs) {
-  return backend_->Load(certs);
+void SQLiteServerBoundCertStore::Load(
+    const LoadedCallback& loaded_callback) {
+  backend_->Load(loaded_callback);
 }
 
 void SQLiteServerBoundCertStore::AddServerBoundCert(