Include referrer chain with inline install requests.

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 84f1905e3959975cd4237ff408facc824ade74e4..425fb1fbec99e8789066262aa821b17a0976ce8f 100644
--- a/chrome/browser/extensions/webstore_standalone_installer.cc
+++ b/chrome/browser/extensions/webstore_standalone_installer.cc
@@ -69,6 +69,11 @@ void WebstoreStandaloneInstaller::BeginInstall() {
       profile_->GetRequestContext(),
       GetRequestorURL(),
       id_));
+
+  std::string json_post_data = GetJsonPostData();
+  if (!json_post_data.empty())
+    webstore_data_fetcher_->SetJsonPostData(json_post_data);
+
   webstore_data_fetcher_->Start();
 }
 
@@ -159,6 +164,10 @@ void WebstoreStandaloneInstaller::InitInstallData(
   // Default implementation sets no properties.
 }
 
+std::string WebstoreStandaloneInstaller::GetJsonPostData() {
+  return std::string();
+}
+
 void WebstoreStandaloneInstaller::OnManifestParsed() {
   ProceedWithInstallPrompt();
 }