add pause button for resumable in-progress downloads.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java
index dd110a83ca38df459e3ecbfa63c8cb995b71ae63..64e167b8be2613d0d360abafbff01b72020eec63 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java
@@ -1120,14 +1120,24 @@ public class DownloadManagerService extends BroadcastReceiver implements
         nativeCancelDownload(mNativeDownloadManagerService, downloadId);
     }
 
+    /**
+     * Called to pause a download.
+     * @param downloadId Id of the download.
+     */
+    void pauseDownload(int downloadId) {
+        nativePauseDownload(mNativeDownloadManagerService, downloadId);
+    }
+
     @CalledByNative
     void onResumptionFailed(int downloadId, String fileName) {
         mDownloadNotifier.notifyDownloadFailed(
                 new DownloadInfo.Builder().setDownloadId(downloadId).setFileName(fileName).build());
+        removePendingDownloadFromSharedPrefs(downloadId);
     }
 
     private native long nativeInit();
     private native void nativeResumeDownload(
             long nativeDownloadManagerService, int downloadId, String fileName);
     private native void nativeCancelDownload(long nativeDownloadManagerService, int downloadId);
+    private native void nativePauseDownload(long nativeDownloadManagerService, int downloadId);
 }