Add Storage.Blob.BlobUrlLoader.FailureType UMA

This parallels Storage.Blob.FileReaderLoader.FailureType, but for blobs
loaded by url instead.

Bug: 1001677
Change-Id: I9fd5a75d71fe03b80acacd55fd82b6569df9c985
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1788457Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Auto-Submit: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695358}

storage/browser/blob/blob_url_loader.cc

@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -192,6 +193,9 @@ void BlobURLLoader::DidReadSideData(net::IOBufferWithSize* data) {
 
 void BlobURLLoader::OnComplete(net::Error error_code,
                                uint64_t total_written_bytes) {
+  base::UmaHistogramSparse("Storage.Blob.BlobUrlLoader.FailureType",
+                           error_code);
+
   network::URLLoaderCompletionStatus status(error_code);
   status.encoded_body_length = total_written_bytes;
   status.decoded_body_length = total_written_bytes;

tools/metrics/histograms/histograms.xml

@@ -137580,6 +137580,16 @@ should be kept until we use this API.  -->
   </summary>
 </histogram>
 
+<histogram name="Storage.Blob.BlobUrlLoader.FailureType" enum="NetErrorCodes"
+    expires_after="M81">
+  <owner>dmurph@chromium.org</owner>
+  <owner>enne@chromium.org</owner>
+  <summary>
+    Recorded when an error occurs in the BlobUrlLoader, which is used to load
+    blobs from urls in the Renderer.
+  </summary>
+</histogram>
+
 <histogram name="Storage.Blob.Broken" enum="BooleanBroken" expires_after="M87">
   <owner>dmurph@chromium.org</owner>
   <summary>