Introduce a stable set of errors for inline install

chrome/browser/extensions/webstore_standalone_installer.cc

Index: chrome/browser/extensions/webstore_standalone_installer.cc
diff --git a/chrome/browser/extensions/webstore_standalone_installer.cc b/chrome/browser/extensions/webstore_standalone_installer.cc
index 9eba52f7de5edc7d77bd167f484c1d32f26e7066..54d8d421f47fe7b4127cf247fd5b171b4a39acef 100644
--- a/chrome/browser/extensions/webstore_standalone_installer.cc
+++ b/chrome/browser/extensions/webstore_standalone_installer.cc
@@ -59,7 +59,7 @@ void WebstoreStandaloneInstaller::BeginInstall() {
     return;
   }
 
-  webstore_install::Result result = webstore_install::UNKNOWN_ERROR;
+  webstore_install::Result result = webstore_install::OTHER_ERROR;
   std::string error;
   if (!EnsureUniqueInstall(&result, &error)) {
     CompleteInstall(result, error);
@@ -124,7 +124,7 @@ void WebstoreStandaloneInstaller::CompleteInstall(
     const std::string& error) {
   scoped_active_install_.reset();
   if (!callback_.is_null())
-    callback_.Run(result == webstore_install::SUCCESS, error);
+    callback_.Run(result == webstore_install::SUCCESS, error, result);
   Release();  // Matches the AddRef in BeginInstall.
 }
 
@@ -306,7 +306,7 @@ void WebstoreStandaloneInstaller::OnWebstoreParseFailure(
     const std::string& id,
     InstallHelperResultCode result_code,
     const std::string& error_message) {
-  webstore_install::Result install_result = webstore_install::UNKNOWN_ERROR;
+  webstore_install::Result install_result = webstore_install::OTHER_ERROR;
   switch (result_code) {
     case WebstoreInstallHelper::Delegate::MANIFEST_ERROR:
       install_result = webstore_install::INVALID_MANIFEST;
@@ -400,7 +400,7 @@ void WebstoreStandaloneInstaller::OnExtensionInstallFailure(
     WebstoreInstaller::FailureReason reason) {
   CHECK_EQ(id_, id);
 
-  webstore_install::Result install_result = webstore_install::UNKNOWN_ERROR;
+  webstore_install::Result install_result = webstore_install::OTHER_ERROR;
   switch (reason) {
     case WebstoreInstaller::FAILURE_REASON_CANCELLED:
       install_result = webstore_install::USER_CANCELLED;