Add more download cancel reasons to study silently failing download

Some downloads are cancelled silently without obvious reasons.
This CL adds more enums to figure out those.

BUG=1180747

Change-Id: I5354793cafc52c7b51317f5507383e279193a6a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2816191
Commit-Queue: Min Qin <qinmin@chromium.org>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#871125}

chrome/browser/download/download_stats.h

@@ -102,7 +102,15 @@ enum class DownloadCancelReason {
   kExistingDownloadPath = 0,
   // Canceled due to download target determiner confirmation result.
   kTargetConfirmationResult = 1,
-  kMaxValue = kTargetConfirmationResult
+  // Canceled due to no valid virtual path.
+  kNoValidPath = 2,
+  // Canceled due to no mixed content.
+  kMixedContent = 3,
+  // Canceled due to failed path reservacation.
+  kFailedPathReservation = 4,
+  // Canceled due to empty local path.
+  kEmptyLocalPath = 5,
+  kMaxValue = kEmptyLocalPath
 };
 
 // Increment one of the above counts.

chrome/browser/download/download_target_determiner.cc

@@ -210,6 +210,7 @@ DownloadTargetDeterminer::Result
       // target determination process and wait for self deletion.
       RecordDownloadPathGeneration(DownloadPathGenerationEvent::NO_VALID_PATH,
                                    true);
+      RecordDownloadCancelReason(DownloadCancelReason::kNoValidPath);
       ScheduleCallbackAndDeleteSelf(
           download::DOWNLOAD_INTERRUPT_REASON_USER_CANCELED);
       return QUIT_DOLOOP;
@@ -350,6 +351,7 @@ void DownloadTargetDeterminer::GetMixedContentStatusDone(
   mixed_content_status_ = status;
 
   if (status == download::DownloadItem::MixedContentStatus::SILENT_BLOCK) {
+    RecordDownloadCancelReason(DownloadCancelReason::kMixedContent);
     ScheduleCallbackAndDeleteSelf(
         download::DOWNLOAD_INTERRUPT_REASON_FILE_BLOCKED);
     return;
@@ -459,6 +461,8 @@ void DownloadTargetDeterminer::ReserveVirtualPathDone(
       case download::PathValidationResult::PATH_NOT_WRITABLE:
       case download::PathValidationResult::NAME_TOO_LONG:
       case download::PathValidationResult::CONFLICT:
+        RecordDownloadCancelReason(
+            DownloadCancelReason::kFailedPathReservation);
         ScheduleCallbackAndDeleteSelf(
             download::DOWNLOAD_INTERRUPT_REASON_USER_CANCELED);
         return;
@@ -600,6 +604,7 @@ void DownloadTargetDeterminer::DetermineLocalPathDone(
     // Google Drive logic (e.g. filesystem error while trying to create the
     // cache file). We are going to return a generic error here since a more
     // specific one is unlikely to be helpful to the user.
+    RecordDownloadCancelReason(DownloadCancelReason::kEmptyLocalPath);
     ScheduleCallbackAndDeleteSelf(
         download::DOWNLOAD_INTERRUPT_REASON_FILE_FAILED);
     return;

tools/metrics/histograms/enums.xml

@@ -19875,6 +19875,10 @@ Called by update_document_policy_enum.py.-->
 <enum name="DownloadCancelReason">
   <int value="0" label="Existing download path"/>
   <int value="1" label="Target confirmation result"/>
+  <int value="2" label="No valid path"/>
+  <int value="3" label="Mixed content"/>
+  <int value="4" label="Failed path reservation"/>
+  <int value="5" label="Empty local path"/>
 </enum>
 
 <enum name="DownloadConnectionSecurity">