STH Set: Delay loading until after start-up.

chrome/browser/component_updater/sth_set_component_installer.cc

Index: chrome/browser/component_updater/sth_set_component_installer.cc
diff --git a/chrome/browser/component_updater/sth_set_component_installer.cc b/chrome/browser/component_updater/sth_set_component_installer.cc
index b6ced0134ef16a261d8719e72d851bbaeb5ac705..b4294f865cff91adf3cb817a847965d70585c813 100644
--- a/chrome/browser/component_updater/sth_set_component_installer.cc
+++ b/chrome/browser/component_updater/sth_set_component_installer.cc
@@ -16,8 +16,10 @@
 #include "base/values.h"
 #include "base/version.h"
 #include "chrome/browser/net/sth_distributor_provider.h"
+#include "chrome/common/chrome_features.h"
 #include "components/component_updater/component_updater_paths.h"
 #include "components/safe_json/safe_json_parser.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "crypto/sha2.h"
 #include "net/cert/ct_log_response_parser.h"
@@ -51,7 +53,7 @@ const char kSTHSetFetcherManifestName[] = "Signed Tree Heads";
 
 STHSetComponentInstallerTraits::STHSetComponentInstallerTraits(
     net::ct::STHObserver* sth_observer)
-    : sth_observer_(sth_observer) {}
+    : sth_observer_(sth_observer), weak_ptr_factory_(this) {}
 
 STHSetComponentInstallerTraits::~STHSetComponentInstallerTraits() {}
 
@@ -74,12 +76,19 @@ 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();
+  const base::Closure load_sths_closure = base::Bind(
+      &STHSetComponentInstallerTraits::LoadSTHsFromDisk,
+      weak_ptr_factory_.GetWeakPtr(), GetInstalledPath(install_dir), version);
+
+  if (variations::GetVariationParamValueByFeature(features::kSTHSetComponent,
+                                                  "delayed_load") != "no") {
+    DVLOG(1) << "Delaying STHSet load until after start-up.";
+    content::BrowserThread::PostAfterStartupTask(
+        FROM_HERE, content::BrowserThread::GetBlockingPool(),
+        load_sths_closure);
+  } else {
+    DVLOG(1) << "Loading STHSet during start-up.";
+    content::BrowserThread::PostBlockingPoolTask(FROM_HERE, load_sths_closure);
   }
 }