STH Set: Delay loading until after start-up.

chrome/browser/component_updater/sth_set_component_installer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/component_updater/sth_set_component_installer.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_enumerator.h"
@@ skipping 56 matching lines @@
 bool STHSetComponentInstallerTraits::OnCustomInstall(
     const base::DictionaryValue& manifest,
     const base::FilePath& install_dir) {
   return true;  // Nothing custom here.
 }
 
 void STHSetComponentInstallerTraits::ComponentReady(
     const base::Version& version,
     const base::FilePath& install_dir,
     std::unique_ptr<base::DictionaryValue> manifest) {
-  if (!content::BrowserThread::PostBlockingPoolTask(
-          FROM_HERE,
-          base::Bind(&STHSetComponentInstallerTraits::LoadSTHsFromDisk,
-                     base::Unretained(this), GetInstalledPath(install_dir),
-                     version))) {
-    NOTREACHED();
-  }
+  content::BrowserThread::PostAfterStartupTask(

[Alexei Svitkine (slow), 2016/07/12 14:56:09]

Per comment on the bug, please keep the old behavior as well and use variations
params (go/variations-params) to choose one behavior over the other.

This way, we can confirm with an experiment that this change is working as
expected.

[Eran Messeri, 2016/07/12 16:14:42]

Done.

+      FROM_HERE, content::BrowserThread::GetBlockingPool(),
+      base::Bind(&STHSetComponentInstallerTraits::PostStartupLoadSTHsFromDisk,

[waffles, 2016/07/12 13:56:59]

Why not directly post LoadSTHsFromDisk? (I'm not sure what the purpose of
PostStartupLoadSTHsFromDisk is.)

[Eran Messeri, 2016/07/12 16:14:42]

No reason really, removed.

+                 base::Unretained(this), install_dir, version));
 }
 
 // Called during startup and installation before ComponentReady().
 bool STHSetComponentInstallerTraits::VerifyInstallation(
     const base::DictionaryValue& manifest,
     const base::FilePath& install_dir) const {
   return base::PathExists(GetInstalledPath(install_dir));
 }
 
 base::FilePath STHSetComponentInstallerTraits::GetRelativeInstallDir() const {
   return base::FilePath(FILE_PATH_LITERAL("CertificateTransparency"));
 }
 
 void STHSetComponentInstallerTraits::GetHash(std::vector<uint8_t>* hash) const {
   hash->assign(std::begin(kPublicKeySHA256), std::end(kPublicKeySHA256));
 }
 
 std::string STHSetComponentInstallerTraits::GetName() const {
   return kSTHSetFetcherManifestName;
 }
 
 update_client::InstallerAttributes
 STHSetComponentInstallerTraits::GetInstallerAttributes() const {
   return update_client::InstallerAttributes();
 }
 
+void STHSetComponentInstallerTraits::PostStartupLoadSTHsFromDisk(
+    const base::FilePath& install_dir,
+    const base::Version& version) {
+  if (!content::BrowserThread::PostBlockingPoolTask(
+          FROM_HERE,
+          base::Bind(&STHSetComponentInstallerTraits::LoadSTHsFromDisk,
+                     base::Unretained(this), GetInstalledPath(install_dir),
+                     version))) {
+    NOTREACHED();
+  }
+}
+
 void STHSetComponentInstallerTraits::LoadSTHsFromDisk(
     const base::FilePath& sths_path,
     const base::Version& version) {
   if (sths_path.empty())
     return;
 
   base::FileEnumerator sth_file_enumerator(sths_path, false,
                                            base::FileEnumerator::FILES,
                                            FILE_PATH_LITERAL("*.sth"));
   base::FilePath sth_file_path;
@@ skipping 71 matching lines @@
 
   std::unique_ptr<ComponentInstallerTraits> traits(
       new STHSetComponentInstallerTraits(distributor));
   // |cus| will take ownership of |installer| during installer->Register(cus).
   DefaultComponentInstaller* installer =
       new DefaultComponentInstaller(std::move(traits));
   installer->Register(cus, base::Closure());
 }
 
 }  // namespace component_updater