Show download error message if sdcard is not available

chrome/browser/download/download_path_reservation_tracker.cc

Index: chrome/browser/download/download_path_reservation_tracker.cc
diff --git a/chrome/browser/download/download_path_reservation_tracker.cc b/chrome/browser/download/download_path_reservation_tracker.cc
index 6f5603e3cd5531094121b5ebd8efb2d92bec6fe0..014a96e05cdf4ad4094235de840e0bf04b602144 100644
--- a/chrome/browser/download/download_path_reservation_tracker.cc
+++ b/chrome/browser/download/download_path_reservation_tracker.cc
@@ -164,7 +164,6 @@ bool CreateReservation(
     base::FilePath* reserved_path) {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
   DCHECK(suggested_path.IsAbsolute());
-
   // Create a reservation map if one doesn't exist. It will be automatically
   // deleted when all the reservations are revoked.
   if (g_reservation_map == NULL)
@@ -202,9 +201,15 @@ bool CreateReservation(
   // to the user's "My Documents" directory. We'll prompt them in this case.
   if (!base::PathIsWritable(target_dir)) {
     DVLOG(1) << "Unable to write to directory \"" << target_dir.value() << "\"";
+#if defined(OS_ANDROID)

[asanka, 2016/07/07 21:12:48]

This code is conditioned on OS_ANDROID while the only logic that intercepts the
resulting state (!verified && path.empty()) is conditioned on
BUILDFLAG(ANDROID_JAVA_UI). Let's pick one.

[qinmin, 2016/07/07 22:49:37]

Done.

+    // On Android, file will not be by other apps if it is downloaded to
+    // Chrome's own directory.

[asanka, 2016/07/07 21:12:48]

The comment should mention that DIR_USER_DOCUMENTS is in reality a subdirectory
of DIR_ANDROID_APP_DATA which isn't accessible by other apps.

Also explicitly clear |reserved_path| here.

[qinmin, 2016/07/07 22:49:37]

Done.

+    return false;
+#else
     is_path_writeable = false;
     PathService::Get(chrome::DIR_USER_DOCUMENTS, &target_dir);
     target_path = target_dir.Append(filename);
+#endif
   }
 
   if (is_path_writeable) {