Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

components/component_updater/default_component_installer.cc

Index: components/component_updater/default_component_installer.cc
diff --git a/components/component_updater/default_component_installer.cc b/components/component_updater/default_component_installer.cc
index 6588973281ccb2aa5f8c065c686228486560c6d7..4713a9b902ff391ad668b81fd0f4dc60872f56aa 100644
--- a/components/component_updater/default_component_installer.cc
+++ b/components/component_updater/default_component_installer.cc
@@ -17,16 +17,43 @@
 #include "components/component_updater/component_updater_service.h"
 #include "components/component_updater/default_component_installer.h"
 #include "components/update_client/component_unpacker.h"
-#include "components/update_client/update_client.h"
+#include "components/update_client/utils.h"
 
 using update_client::CrxComponent;
 
 namespace component_updater {
 
 namespace {
+
 // Version "0" corresponds to no installed version. By the server's conventions,
 // we represent it as a dotted quad.
 const char kNullVersion[] = "0.0.0.0";
+
+void UninstallOnTaskRunner(const base::FilePath& base_dir) {
+  std::vector<base::FilePath> paths;
+  base::FileEnumerator file_enumerator(
+      base_dir, false, base::FileEnumerator::DIRECTORIES);
+  for (base::FilePath path = file_enumerator.Next();
+       !path.value().empty();
+       path = file_enumerator.Next()) {
+    base::Version version(path.BaseName().MaybeAsASCII());
+
+    // Ignore folders that don't have valid version names. These folders are not
+    // managed by the component installer, so do not try to remove them.
+    if (!version.IsValid())
+      continue;
+
+    if (!base::DeleteFile(path, true))
+      DLOG(ERROR) << "Couldn't delete " << path.value();
+  }
+
+  // Delete the base directory if it's empty now.
+  if (base::IsDirectoryEmpty(base_dir)) {
+    if (base::DeleteFile(base_dir, false))
+      DLOG(ERROR) << "Couldn't delete " << base_dir.value();
+  }
+}
+
 }  // namespace
 
 ComponentInstallerTraits::~ComponentInstallerTraits() {
@@ -35,12 +62,18 @@ ComponentInstallerTraits::~ComponentInstallerTraits() {
 DefaultComponentInstaller::DefaultComponentInstaller(
     scoped_ptr<ComponentInstallerTraits> installer_traits)
     : current_version_(kNullVersion),
+      should_uninstall_on_destruction_(false),
       main_task_runner_(base::MessageLoopProxy::current()) {
   installer_traits_ = installer_traits.Pass();
 }
 
 DefaultComponentInstaller::~DefaultComponentInstaller() {
   DCHECK(thread_checker_.CalledOnValidThread());
+  if (should_uninstall_on_destruction_) {
+      task_runner_->PostTask(FROM_HERE,
+                             base::Bind(&UninstallOnTaskRunner,
+                                        installer_traits_->GetBaseDirectory()));
+  }
 }
 
 void DefaultComponentInstaller::Register(ComponentUpdateService* cus) {
@@ -78,6 +111,8 @@ bool DefaultComponentInstaller::InstallHelper(
 
 bool DefaultComponentInstaller::Install(const base::DictionaryValue& manifest,
                                         const base::FilePath& unpack_path) {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+
   std::string manifest_version;
   manifest.GetStringASCII("version", &manifest_version);
   base::Version version(manifest_version.c_str());
@@ -123,6 +158,19 @@ bool DefaultComponentInstaller::GetInstalledFile(
   return true;
 }
 
+void DefaultComponentInstaller::Unregister(ComponentUpdateService* cus) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  CrxComponent crx;
+  installer_traits_->GetHash(&crx.pk_hash);
+  ComponentUpdateService::Status status =
+      cus->UnregisterComponent(GetCrxComponentID(crx));
+  DCHECK_EQ(ComponentUpdateService::kOk, status);
+
+  // Wait with uninstallation until all references have been dropped.
+  should_uninstall_on_destruction_ = true;
+}
+
 void DefaultComponentInstaller::StartRegistration(ComponentUpdateService* cus) {
   DCHECK(task_runner_.get());
   DCHECK(task_runner_->RunsTasksOnCurrentThread());