Code:   void Start() {
    DVLOG(2) << "Starting SafeBrowsing download check for: "
             << item_->DebugString(true);
    DCHECK_CURRENTLY_ON(BrowserThread::UI);
    DownloadCheckResultReason reason = REASON_MAX;
    if (!IsSupportedDownload(
        *item_, item_->GetTargetFilePath(), &reason, &type_)) {
      switch (reason) {
        case REASON_EMPTY_URL_CHAIN:
        case REASON_INVALID_URL:
        case REASON_UNSUPPORTED_URL_SCHEME:
          PostFinishTask(UNKNOWN, reason);
          return;

        case REASON_NOT_BINARY_FILE:
          RecordFileExtensionType(item_->GetTargetFilePath());
          PostFinishTask(UNKNOWN, reason);
          return;

        default:
          NOTREACHED();
      }
    }
    RecordFileExtensionType(item_->GetTargetFilePath());

     if (item_->GetTargetFilePath().MatchesExtension(
         FILE_PATH_LITERAL(".zip"))) {
       StartExtractZipFeatures();
     } else {
       DCHECK(!download_protection_util::IsArchiveFile(
           item_->GetTargetFilePath()));
      StartExtractFileFeatures();
    }
  }

Vulnerability Type: Bypass 
CWE ID: 
Summary: Multiple unspecified vulnerabilities in Google Chrome before 33.0.1750.117 allow attackers to bypass the sandbox protection mechanism after obtaining renderer access, or have other impact, via unknown vectors.
Commit Message: Add the SandboxedDMGParser and wire it up to the DownloadProtectionService.

BUG=496898,464083
R=isherman@chromium.org, kenrb@chromium.org, mattm@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/1299223006 .

Cr-Commit-Position: refs/heads/master@{#344876}