ui: Cleanup class/struct forward declarations

extensions/browser/updater/update_install_shim.cc

Index: extensions/browser/updater/update_install_shim.cc
diff --git a/extensions/browser/updater/update_install_shim.cc b/extensions/browser/updater/update_install_shim.cc
index 4072a85d1d774932663baf0fc78d9e7309cb6680..671303b7598cf485d21393546570f8bab9af4f9b 100644
--- a/extensions/browser/updater/update_install_shim.cc
+++ b/extensions/browser/updater/update_install_shim.cc
@@ -11,10 +11,16 @@
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/values.h"
+#include "components/update_client/update_client_errors.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace extensions {
 
+namespace {
+using InstallError = update_client::InstallError;
+using Result = update_client::CrxInstaller::Result;
+}  // namespace
+
 UpdateInstallShim::UpdateInstallShim(std::string extension_id,
                                      const base::FilePath& extension_root,
                                      const UpdateInstallShimCallback& callback)
@@ -26,11 +32,11 @@ void UpdateInstallShim::OnUpdateError(int error) {
   VLOG(1) << "OnUpdateError (" << extension_id_ << ") " << error;
 }
 
-bool UpdateInstallShim::Install(const base::DictionaryValue& manifest,
-                                const base::FilePath& unpack_path) {
+Result UpdateInstallShim::Install(const base::DictionaryValue& manifest,
+                                  const base::FilePath& unpack_path) {
   base::ScopedTempDir temp_dir;
   if (!temp_dir.CreateUniqueTempDir())
-    return false;
+    return Result(InstallError::GENERIC_ERROR);
 
   // The UpdateClient code will delete unpack_path if it still exists after
   // this method is done, so we rename it on top of our temp dir.
@@ -39,13 +45,13 @@ bool UpdateInstallShim::Install(const base::DictionaryValue& manifest,
     LOG(ERROR) << "Trying to install update for " << extension_id_
                << "and failed to move " << unpack_path.value() << " to  "
                << temp_dir.GetPath().value();
-    return false;
+    return Result(InstallError::GENERIC_ERROR);
   }
   content::BrowserThread::PostTask(
       content::BrowserThread::UI, FROM_HERE,
       base::Bind(&UpdateInstallShim::RunCallbackOnUIThread, this,
                  temp_dir.Take()));
-  return true;
+  return Result(InstallError::NONE);
 }
 
 bool UpdateInstallShim::GetInstalledFile(const std::string& file,