Properly encode raw digest of a download to make it UTF8 safe

DownloadItem::GetHash() returns raw SHA-256 hash that is not hex encoded.
This may cause DCHCEK failure when passing on the
DangerousDownloadInfo::ToValue() since the raw hash may not be UTF8.
Therefore, this CL HexEncode the raw sha256 first before passing onto the
event router.

Bug: 846156,796087
Change-Id: Iab51535d7de0b37841851b4887ffca9cf099bd39
Reviewed-on: https://chromium-review.googlesource.com/1079436Reviewed-by: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Jialiu Lin <jialiul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563039}

chrome/browser/safe_browsing/download_protection/download_protection_service.cc

@@ -498,10 +498,12 @@ void DownloadProtectionService::OnDangerousDownloadOpened(
       signin_manager ? signin_manager->GetAuthenticatedAccountInfo().email
                      : std::string();
 
+  std::string raw_digest_sha256 = item->GetHash();
   extensions::SafeBrowsingPrivateEventRouterFactory::GetForProfile(profile)
-      ->OnDangerousDownloadOpened(item->GetURL(),
-                                  item->GetTargetFilePath().AsUTF8Unsafe(),
-                                  item->GetHash(), username);
+      ->OnDangerousDownloadOpened(
+          item->GetURL(), item->GetTargetFilePath().AsUTF8Unsafe(),
+          base::HexEncode(raw_digest_sha256.data(), raw_digest_sha256.size()),
+          username);
 }
 
 }  // namespace safe_browsing

chrome/browser/safe_browsing/download_protection/download_protection_service_unittest.cc

@@ -2528,7 +2528,8 @@ TEST_F(DownloadProtectionServiceTest, VerifyDangerousDownloadOpenedAPICall) {
   auto captured_args = event_observer.PassEventArgs().GetList()[0].Clone();
   EXPECT_EQ("http://example.com/a.exe",
             captured_args.FindKey("url")->GetString());
-  EXPECT_EQ(hash, captured_args.FindKey("downloadDigestSha256")->GetString());
+  EXPECT_EQ(base::HexEncode(hash.data(), hash.size()),
+            captured_args.FindKey("downloadDigestSha256")->GetString());
   EXPECT_EQ(target_path.MaybeAsASCII(),
             captured_args.FindKey("fileName")->GetString());