Simplify ExtensionInstallChecker into a single-use class

chrome/browser/extensions/extension_install_checker.cc

Index: chrome/browser/extensions/extension_install_checker.cc
diff --git a/chrome/browser/extensions/extension_install_checker.cc b/chrome/browser/extensions/extension_install_checker.cc
index 313225df59060d09c967dd4cf239bc78eb43db8f..877f1d48d5319960ea40a74ea184171391054d2d 100644
--- a/chrome/browser/extensions/extension_install_checker.cc
+++ b/chrome/browser/extensions/extension_install_checker.cc
@@ -14,15 +14,17 @@
 
 namespace extensions {
 
-ExtensionInstallChecker::ExtensionInstallChecker(Profile* profile)
+ExtensionInstallChecker::ExtensionInstallChecker(
+    Profile* profile,
+    scoped_refptr<const Extension> extension)
     : profile_(profile),
+      extension_(extension),
       blacklist_state_(NOT_BLACKLISTED),
       policy_allows_load_(true),
-      current_sequence_number_(0),
+      enabled_checks_(0),
       running_checks_(0),
       fail_fast_(false),
-      weak_ptr_factory_(this) {
-}
+      weak_ptr_factory_(this) {}
 
 ExtensionInstallChecker::~ExtensionInstallChecker() {
 }
@@ -30,6 +32,9 @@ ExtensionInstallChecker::~ExtensionInstallChecker() {
 void ExtensionInstallChecker::Start(int enabled_checks,
                                     bool fail_fast,
                                     const Callback& callback) {
+  DCHECK_EQ(enabled_checks_, 0)
+      << "ExtensionInstallChecker::Start() can be called at most once";
+
   // Profile is null in tests.
   if (profile_) {
     DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
@@ -44,10 +49,10 @@ void ExtensionInstallChecker::Start(int enabled_checks,
     return;
   }
 
+  enabled_checks_ = enabled_checks;

[Devlin, 2017/03/16 19:29:40]

With this class becoming single use, we can move a lot of these to the ctor.

[michaelpg, 2017/03/17 04:25:23]

Done.

   running_checks_ = enabled_checks;
   fail_fast_ = fail_fast;
   callback_ = callback;
-  ResetResults();
 
   // Execute the management policy check first as it is synchronous.
   if (enabled_checks & CHECK_MANAGEMENT_POLICY) {
@@ -92,17 +97,14 @@ void ExtensionInstallChecker::CheckRequirements() {
   if (!requirements_checker_.get())
     requirements_checker_.reset(new ChromeRequirementsChecker());
   requirements_checker_->Check(
-      extension_,
-      base::Bind(&ExtensionInstallChecker::OnRequirementsCheckDone,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 current_sequence_number_));
+      extension_, base::Bind(&ExtensionInstallChecker::OnRequirementsCheckDone,
+                             weak_ptr_factory_.GetWeakPtr()));
 }
 
 void ExtensionInstallChecker::OnRequirementsCheckDone(
-    int sequence_number,
     const std::vector<std::string>& errors) {
   // Some pending results may arrive after fail fast.
-  if (sequence_number != current_sequence_number_)
+  if (!is_running())
     return;
 
   requirement_errors_ = errors;
@@ -118,14 +120,12 @@ void ExtensionInstallChecker::CheckBlacklistState() {
   blacklist->IsBlacklisted(
       extension_->id(),
       base::Bind(&ExtensionInstallChecker::OnBlacklistStateCheckDone,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 current_sequence_number_));
+                 weak_ptr_factory_.GetWeakPtr()));
 }
 
-void ExtensionInstallChecker::OnBlacklistStateCheckDone(int sequence_number,
-                                                        BlacklistState state) {
+void ExtensionInstallChecker::OnBlacklistStateCheckDone(BlacklistState state) {
   // Some pending results may arrive after fail fast.
-  if (sequence_number != current_sequence_number_)
+  if (!is_running())
     return;
 
   blacklist_state_ = state;
@@ -134,13 +134,6 @@ void ExtensionInstallChecker::OnBlacklistStateCheckDone(int sequence_number,
   MaybeInvokeCallback();
 }
 
-void ExtensionInstallChecker::ResetResults() {
-  requirement_errors_.clear();
-  blacklist_state_ = NOT_BLACKLISTED;
-  policy_allows_load_ = true;
-  policy_error_.clear();
-}
-
 void ExtensionInstallChecker::MaybeInvokeCallback() {
   if (callback_.is_null())
     return;
@@ -160,7 +153,6 @@ void ExtensionInstallChecker::MaybeInvokeCallback() {
     // If we are failing fast, discard any pending results.
     weak_ptr_factory_.InvalidateWeakPtrs();
     running_checks_ = 0;
-    ++current_sequence_number_;
 
     Callback callback_copy = callback_;
     callback_.Reset();