Revert "Disable NotificationImageReporterTest."

This reverts commit da17415d.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 553230 as the
culprit for failures in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyRAsSDVdmU3VzcGVjdGVkQ0wiMWNocm9taXVtL2RhMTc0MTVkMTg4ODRmYjQ3NDUxYmIyN2ZjOWYzMDg3ZmRiMzc5MTUM

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.linux/Linux%20Builder/101940

Sample Failed Step: compile

Original change's description:
> Disable NotificationImageReporterTest.
> 
> Its use of feature flags causes data races.
> 
> BUG=836359
> TBR=xidachen@chromium.org
> NOTRY=true
> 
> Change-Id: I5bc92a6fc9b9010b9863b363dc3033b95f777762
> Reviewed-on: https://chromium-review.googlesource.com/1026462
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Commit-Queue: Lei Zhang <thestig@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#553230}

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
BUG=836359

Change-Id: I748cc7ee9c5dd97a74d10dfdd77161966cff86b8
Reviewed-on: https://chromium-review.googlesource.com/1026433
Cr-Commit-Position: refs/heads/master@{#553241}

chrome/browser/safe_browsing/notification_image_reporter_unittest.cc

@@ -192,8 +192,7 @@ void NotificationImageReporterTest::ReportNotificationImage() {
       image_);
 }
 
-// Disabled due to data race. https://crbug.com/836359
-TEST_F(NotificationImageReporterTest, DISABLED_ReportSuccess) {
+TEST_F(NotificationImageReporterTest, ReportSuccess) {
   SetExtendedReportingLevel(SBER_LEVEL_SCOUT);
 
   ReportNotificationImage();
@@ -218,8 +217,7 @@ TEST_F(NotificationImageReporterTest, DISABLED_ReportSuccess) {
   EXPECT_FALSE(report.image().has_original_dimensions());
 }
 
-// Disabled due to data race. https://crbug.com/836359
-TEST_F(NotificationImageReporterTest, DISABLED_ImageDownscaling) {
+TEST_F(NotificationImageReporterTest, ImageDownscaling) {
   SetExtendedReportingLevel(SBER_LEVEL_SCOUT);
 
   image_ = CreateBitmap(640 /* w */, 360 /* h */);
@@ -240,8 +238,7 @@ TEST_F(NotificationImageReporterTest, DISABLED_ImageDownscaling) {
   EXPECT_EQ(360, report.image().original_dimensions().height());
 }
 
-// Disabled due to data race. https://crbug.com/836359
-TEST_F(NotificationImageReporterTest, DISABLED_NoReportWithoutSBER) {
+TEST_F(NotificationImageReporterTest, NoReportWithoutSBER) {
   SetExtendedReportingLevel(SBER_LEVEL_OFF);
 
   ReportNotificationImage();
@@ -250,8 +247,7 @@ TEST_F(NotificationImageReporterTest, DISABLED_NoReportWithoutSBER) {
   EXPECT_EQ(0, notification_image_reporter_->sent_report_count());
 }
 
-// Disabled due to data race. https://crbug.com/836359
-TEST_F(NotificationImageReporterTest, DISABLED_NoReportWithoutScout) {
+TEST_F(NotificationImageReporterTest, NoReportWithoutScout) {
   SetExtendedReportingLevel(SBER_LEVEL_LEGACY);
 
   ReportNotificationImage();
@@ -284,8 +280,7 @@ TEST_F(NotificationImageReporterTest, NoReportOnWhitelistedUrl) {
   EXPECT_EQ(0, notification_image_reporter_->sent_report_count());
 }
 
-// Disabled due to data race. https://crbug.com/836359
-TEST_F(NotificationImageReporterTest, DISABLED_MaxReportsPerDay) {
+TEST_F(NotificationImageReporterTest, MaxReportsPerDay) {
   SetExtendedReportingLevel(SBER_LEVEL_SCOUT);
 
   const int kMaxReportsPerDay = 5;