Update component extension reload backoff logic.

Responding to wez@'s comments in crrev.com/2281323002.

This change removes a BackoffEntry for a component extension if it has loaded and there has been no additional failures for that extension within 60s.

BUG=639104

Review-Url: https://codereview.chromium.org/2310463002
Cr-Commit-Position: refs/heads/master@{#417315}

chrome/browser/background/background_contents_service.cc

@@ -280,7 +280,9 @@ int BackgroundContentsService::restart_delay_in_ms_ = 3000;  // 3 seconds.
 BackgroundContentsService::BackgroundContentsService(
     Profile* profile,
     const base::CommandLine* command_line)
-    : prefs_(NULL), extension_registry_observer_(this) {
+    : prefs_(NULL),
+      extension_registry_observer_(this),
+      weak_ptr_factory_(this) {
   // Don't load/store preferences if the parent profile is incognito.
   if (!profile->IsOffTheRecord())
     prefs_ = profile->GetPrefs();
@@ -478,6 +480,23 @@ void BackgroundContentsService::OnExtensionLoaded(
     }
   }
 
+  // If there is an existing BackoffEntry for the extension, clear it if
+  // the component extension stays loaded for 60 seconds. This avoids the
+  // situation of effectively disabling an extension for the entire browser
+  // session if there was a periodic crash (sometimes caused by another source).
+  if (extensions::Manifest::IsComponentLocation(extension->location())) {
+    ComponentExtensionBackoffEntryMap::const_iterator it =
+        component_backoff_map_.find(extension->id());
+    if (it != component_backoff_map_.end()) {
+      net::BackoffEntry* entry = component_backoff_map_[extension->id()].get();
+      base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(FROM_HERE,
+          base::Bind(&BackgroundContentsService::MaybeClearBackoffEntry,
+              weak_ptr_factory_.GetWeakPtr(), extension->id(),
+              entry->failure_count()),
+          base::TimeDelta::FromSeconds(60));
+    }
+  }
+
   // Close the crash notification balloon for the app/extension, if any.
   ScheduleCloseBalloon(extension->id(), profile);
   SendChangeNotification(profile);
@@ -540,21 +559,21 @@ void BackgroundContentsService::RestartForceInstalledExtensionOnCrash(
   // If the extension was a component extension, use exponential backoff when
   // attempting to reload.
   if (extensions::Manifest::IsComponentLocation(extension->location())) {
-    ExtensionBackoffEntryMap::const_iterator it =
-        backoff_map_.find(extension->id());
+    ComponentExtensionBackoffEntryMap::const_iterator it =
+        component_backoff_map_.find(extension->id());
 
     // Create a BackoffEntry if this is the first time we try to reload this
     // particular extension.
-    if (it == backoff_map_.end()) {
+    if (it == component_backoff_map_.end()) {
       std::unique_ptr<net::BackoffEntry> backoff_entry(
           new net::BackoffEntry(&kExtensionReloadBackoffPolicy));
-      backoff_map_.insert(
+      component_backoff_map_.insert(
           std::pair<extensions::ExtensionId,
                     std::unique_ptr<net::BackoffEntry>>(
               extension->id(), std::move(backoff_entry)));
     }
 
-    net::BackoffEntry* entry = backoff_map_[extension->id()].get();
+    net::BackoffEntry* entry = component_backoff_map_[extension->id()].get();
     entry->InformOfRequest(false);
     restart_delay = entry->GetTimeUntilRelease().InMilliseconds();
   }
@@ -604,6 +623,22 @@ void BackgroundContentsService::SendChangeNotification(Profile* profile) {
       content::Details<BackgroundContentsService>(this));
 }
 
+void BackgroundContentsService::MaybeClearBackoffEntry(
+    const std::string extension_id,
+    int expected_failure_count) {
+  ComponentExtensionBackoffEntryMap::const_iterator it =
+      component_backoff_map_.find(extension_id);
+  if (it == component_backoff_map_.end())
+    return;
+
+  net::BackoffEntry* entry = component_backoff_map_[extension_id].get();
+
+  // Only remove the BackoffEntry if there has has been no failure for
+  // |extension_id| since loading.
+  if (entry->failure_count() == expected_failure_count)
+    component_backoff_map_.erase(it);
+}
+
 void BackgroundContentsService::LoadBackgroundContentsForExtension(
     Profile* profile,
     const std::string& extension_id) {

chrome/browser/background/background_contents_service.h

@@ -14,6 +14,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/background/background_contents.h"
 #include "components/keyed_service/core/keyed_service.h"
@@ -216,6 +217,11 @@ class BackgroundContentsService : private content::NotificationObserver,
   // set of background apps as new background contents are opened/closed).
   void SendChangeNotification(Profile* profile);
 
+  // Checks whether there has been additional |extension_id| failures. If not,
+  // delete the BackoffEntry corresponding to |extension_id|, if exists.
+  void MaybeClearBackoffEntry(const std::string extension_id,
+                              int expected_failure_count);
+
   // Delay (in ms) before restarting a force-installed extension that crashed.
   static int restart_delay_in_ms_;
 
@@ -243,13 +249,15 @@ class BackgroundContentsService : private content::NotificationObserver,
   // Map associating component extensions that have attempted to reload with a
   // BackoffEntry keeping track of retry timing.
   typedef std::map<extensions::ExtensionId, std::unique_ptr<net::BackoffEntry>>
-      ExtensionBackoffEntryMap;
-  ExtensionBackoffEntryMap backoff_map_;
+      ComponentExtensionBackoffEntryMap;
+  ComponentExtensionBackoffEntryMap component_backoff_map_;
 
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
 
+  base::WeakPtrFactory<BackgroundContentsService> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(BackgroundContentsService);
 };