Don't download identical APKs on update.

chrome/browser/android/webapk/webapk_installer.cc

Index: chrome/browser/android/webapk/webapk_installer.cc
diff --git a/chrome/browser/android/webapk/webapk_installer.cc b/chrome/browser/android/webapk/webapk_installer.cc
index 1384c5997f700cfa52b0ab58ec16c26684fcbb19..eb19a21651566eaca2cf65be69c66a714a289d92 100644
--- a/chrome/browser/android/webapk/webapk_installer.cc
+++ b/chrome/browser/android/webapk/webapk_installer.cc
@@ -418,6 +418,12 @@ void WebApkInstaller::OnURLFetchComplete(const net::URLFetcher* source) {
   }
 
   GURL signed_download_url(response->signed_download_url());
+  // https://crbug.com/680131. Don't download identical APKs on update.

[pkotwicz, 2017/01/17 02:37:10]

How about: "The server sends an empty URL if the server does not have a newer
WebAPK to update to."

[Xi Han, 2017/01/17 16:45:12]

Done.

+  if (task_type_ == UPDATE && signed_download_url.is_empty()) {
+    OnSuccess();
+    return;
+  }
+
   if (!signed_download_url.is_valid() || response->package_name().empty()) {
     OnFailure();
     return;