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

chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java
index 91fe99d42ac21f1da611b969f94f09c282aad392..973edc5e535ec7ec3c63e46ce5f21df53c98ec63 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/download/ChromeDownloadDelegateTest.java
@@ -67,4 +67,14 @@ public class ChromeDownloadDelegateTest extends ChromeActivityTestCaseBase<Chrom
         assertFalse(delegate.shouldInterceptContextMenuDownload("http://test/test.dd"));
         assertTrue(delegate.shouldInterceptContextMenuDownload("https://test/test.dm"));
     }
+
+    @SmallTest
+    @Feature({"Download"})
+    public void testGetFileExtension() {
+        assertEquals("ext", ChromeDownloadDelegate.getFileExtension("", "file.ext"));
+        assertEquals("ext", ChromeDownloadDelegate.getFileExtension("http://file.ext", ""));
+        assertEquals("txt", ChromeDownloadDelegate.getFileExtension("http://file.ext", "file.txt"));
+        assertEquals("txt", ChromeDownloadDelegate.getFileExtension(
+                "http://file.ext", "file name.txt"));
+    }
 }