Show download error message if sdcard is not available

chrome/browser/download/download_target_determiner.cc

Index: chrome/browser/download/download_target_determiner.cc
diff --git a/chrome/browser/download/download_target_determiner.cc b/chrome/browser/download/download_target_determiner.cc
index 0c13dcd669467f724a7075fea077b136bc8f5f1e..e4636cd465250817c98e73a7ee85da67dfc097a3 100644
--- a/chrome/browser/download/download_target_determiner.cc
+++ b/chrome/browser/download/download_target_determiner.cc
@@ -40,6 +40,11 @@
 #include "content/public/common/webplugininfo.h"
 #endif
 
+#if defined(OS_ANDROID)
+#include "chrome/browser/android/download/download_controller.h"
+#include "chrome/browser/android/download/download_manager_service.h"
+#endif
+
 #if defined(OS_WIN)
 #include "chrome/browser/ui/pdf/adobe_reader_info_win.h"
 #endif
@@ -317,13 +322,24 @@ void DownloadTargetDeterminer::ReserveVirtualPathDone(
             << " Verified:" << verified;
   DCHECK_EQ(STATE_PROMPT_USER_FOR_DOWNLOAD_PATH, next_state_);
 #if BUILDFLAG(ANDROID_JAVA_UI)
-  // If we cannot reserve the path and the WebContent is already gone, there is
-  // no way to prompt user for an infobar. This could happen when user try to
-  // resume a download after another process has overwritten the same file.
-  // TODO(qinmin): show an error toast to the user. http://crbug.com/581106.
-  if (!verified && !download_->GetWebContents()) {
-    CancelOnFailureAndDeleteSelf();
-    return;
+  if (!verified) {
+    if (path.empty()) {
+      CancelOnFailureAndDeleteSelf();
+      DownloadManagerService::OnDownloadCanceled(
+          download_, DownloadController::CANCEL_REASON_NO_EXTERNAL_STORAGE);
+      return;
+    }
+    if (!download_->GetWebContents()) {
+      // If we cannot reserve the path and the WebContent is already gone, there
+      // is no way to prompt user for an infobar. This could happen when user
+      // try to resume a download after another process has overwritten the same
+      // file.

[asanka, 2016/07/12 17:07:10]

This comment seems wrong. How does a resumption attempt following an overwrite
result in this situation?

[qinmin, 2016/07/12 18:13:04]

should use created instead of overwritten.
When resumption is called, Chrome still checks for path conflict. For example,
if user download file a, then a.crdownload is created. If user kills chrome, and
another process creates a file with name "a" under the download dir, then when
user resumes the download, there will be a conflict.  And since this is
background resumption, webcontents is null.
Modified the comments to describe the situation better

+      CancelOnFailureAndDeleteSelf();
+      DownloadManagerService::OnDownloadCanceled(
+          download_,
+          DownloadController::CANCEL_REASON_CANNOT_DETERMINE_DOWNLOAD_TARGET);
+      return;
+    }
   }
 #endif
   should_prompt_ = (should_prompt_ || !verified);