Fix an issue when parsing extension from file name with white spaces

chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java
index 083f5148cad2ef85c81ced66463ffc1574544cf4..5a786ace914a3d7d623a1a2805d4f2e4a561963f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java
@@ -510,10 +510,7 @@ public class ChromeDownloadDelegate {
                 || "application/force-download".equals(mimeType)
                 || "application/unknown".equals(mimeType)) {
 
-            if (!TextUtils.isEmpty(filename)) {
-                url = filename;
-            }
-            String extension = MimeTypeMap.getFileExtensionFromUrl(url);
+            String extension = getFileExtension(url, filename);
             String newMimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
             if (newMimeType != null) {
                 mimeType = newMimeType;
@@ -527,6 +524,22 @@ public class ChromeDownloadDelegate {
     }
 
     /**
+     * Retrieve the file extension from a given file name or url.
+     *
+     * @param url URL to extract the extension.
+     * @param filename File name to extract the extension.
+     * @return If extension can be extracted from file name, use that. Or otherwise, use the
+     *         extension extracted from the url.
+     */
+    static String getFileExtension(String url, String filename) {
+        if (!TextUtils.isEmpty(filename)) {
+            int index = filename.lastIndexOf(".");
+            if (index > 0) return filename.substring(index + 1);
+        }
+        return MimeTypeMap.getFileExtensionFromUrl(url);
+    }
+
+    /**
      * Check whether a file is dangerous.
      *
      * @param filename Name of the file.