Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

components/component_updater/component_updater_service.cc

Index: components/component_updater/component_updater_service.cc
diff --git a/components/component_updater/component_updater_service.cc b/components/component_updater/component_updater_service.cc
index 4b97baeb31c81a2eedbf39ce8ede6ab7466056d7..bcd324a4ca87468775359fe1555efc38585de23a 100644
--- a/components/component_updater/component_updater_service.cc
+++ b/components/component_updater/component_updater_service.cc
@@ -100,6 +100,7 @@ class CrxUpdateService : public ComponentUpdateService, public OnDemandUpdater {
   Status Start() override;
   Status Stop() override;
   Status RegisterComponent(const CrxComponent& component) override;
+  Status UnregisterComponent(const std::string& crx_id) override;
   std::vector<std::string> GetComponentIDs() const override;
   OnDemandUpdater& GetOnDemandUpdater() override;
   void MaybeThrottle(const std::string& crx_id,
@@ -108,7 +109,7 @@ class CrxUpdateService : public ComponentUpdateService, public OnDemandUpdater {
 
   // Context for a crx download url request.
   struct CRXContext {
-    ComponentInstaller* installer;
+    scoped_refptr<ComponentInstaller> installer;
     std::vector<uint8_t> pk_hash;
     std::string id;
     std::string fingerprint;
@@ -461,6 +462,27 @@ ComponentUpdateService::Status CrxUpdateService::RegisterComponent(
   return kOk;
 }
 
+ComponentUpdateService::Status CrxUpdateService::UnregisterComponent(
+    const std::string& crx_id) {
+  UpdateItems::iterator it = std::find_if(
+      work_items_.begin(), work_items_.end(), CrxUpdateItem::FindById(crx_id));
+  if (it == work_items_.end())
+    return kError;
+
+  CrxUpdateItem* item = *it;
+  CrxUpdateItem::Status status = item->status;
+  if (status == CrxUpdateItem::kDownloading ||
+      status == CrxUpdateItem::kDownloadingDiff ||
+      status == CrxUpdateItem::kUpdating ||
+      status == CrxUpdateItem::kUpdatingDiff) {
+    ChangeItemState(item, CrxUpdateItem::kNoUpdate);
+    ping_manager_->OnUpdateComplete(item);
+  }
+
+  work_items_.erase(it);
+  return kOk;
+}
+
 std::vector<std::string> CrxUpdateService::GetComponentIDs() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   std::vector<std::string> component_ids;
@@ -781,6 +803,23 @@ void CrxUpdateService::DownloadComplete(
   DCHECK(thread_checker_.CalledOnValidThread());
 
   CrxUpdateItem* crx = FindUpdateItemById(crx_context->id);
+
+  // If the item has been removed in the mean time, clean up and return.
+  if (!crx) {
+    crx_downloader_.reset();
+    base::FilePath crx_path = download_result.response;
+    if (!crx_path.empty()) {
+      blocking_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(base::IgnoreResult(
+                         &update_client::DeleteFileAndEmptyParentDirectory),
+                     crx_path));
+    }
+    // Move on to the next update, if there is one available.
+    ScheduleNextRun(kStepDelayMedium);
+    return;
+  }
+
   DCHECK(crx->status == CrxUpdateItem::kDownloadingDiff ||
          crx->status == CrxUpdateItem::kDownloading);
 
@@ -895,6 +934,13 @@ void CrxUpdateService::DoneInstalling(const std::string& component_id,
   const bool is_success = error == ComponentUnpacker::kNone;
 
   CrxUpdateItem* item = FindUpdateItemById(component_id);
+
+  // If the item has been removed in the mean time, return.
+  if (!item) {
+    ScheduleNextRun(kStepDelayMedium);
+    return;
+  }
+
   if (item->status == CrxUpdateItem::kUpdatingDiff && !is_success) {
     item->diff_error_category = error_category;
     item->diff_error_code = error;