Use ukm::SourceId instead of too-small int32_t for UKM reports.

Without this we end up using bogus source ids for reporting to UKM
which end up dropped.

BUG=870407
TEST=none

Change-Id: I6dd43a70dad670613c9bffe440a5f4d8934d3a42
Reviewed-on: https://chromium-review.googlesource.com/1161162Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580337}

components/offline_pages/core/offline_pages_ukm_reporter.cc

@@ -17,7 +17,7 @@ void OfflinePagesUkmReporter::ReportUrlOfflineRequest(const GURL& gurl,
     return;
 
   // This unique ID represents this whole navigation.
-  int32_t source_id = ukm::UkmRecorder::GetNewSourceID();
+  ukm::SourceId source_id = ukm::UkmRecorder::GetNewSourceID();
 
   // Associate the URL with this navigation.
   // TODO(petewil): re-enable once crbug/792197 is addressed.

media/mojo/services/media_metrics_provider.cc

@@ -29,7 +29,7 @@ MediaMetricsProvider::~MediaMetricsProvider() {
   if (!ukm_recorder || !initialized_)
     return;
 
-  const int32_t source_id = ukm_recorder->GetNewSourceID();
+  const ukm::SourceId source_id = ukm_recorder->GetNewSourceID();
 
   // TODO(crbug.com/787209): Stop getting origin from the renderer.
   ukm_recorder->UpdateSourceURL(source_id, untrusted_top_origin_.GetURL());

media/mojo/services/video_decode_perf_history.cc

@@ -282,7 +282,7 @@ void VideoDecodePerfHistory::ReportUkmMetrics(
   if (!ukm_recorder)
     return;
 
-  const int32_t source_id = ukm_recorder->GetNewSourceID();
+  const ukm::SourceId source_id = ukm_recorder->GetNewSourceID();
   ukm::builders::Media_VideoDecodePerfRecord builder(source_id);
 
   // TODO(crbug.com/787209): Stop getting origin from the renderer.

media/mojo/services/watch_time_recorder.cc

@@ -344,7 +344,7 @@ void WatchTimeRecorder::RecordUkmPlaybackData() {
   }
 
   for (auto& ukm_record : ukm_records_) {
-    const int32_t source_id = ukm_recorder->GetNewSourceID();
+    const ukm::SourceId source_id = ukm_recorder->GetNewSourceID();
 
     // TODO(crbug.com/787209): Stop getting origin from the renderer.
     ukm_recorder->UpdateSourceURL(source_id, untrusted_top_origin_.GetURL());