[gcc_build_error] Fix for multiple friend decl of MalwareReportsToggling

Linux desktop gcc build is failing with below error:
In file included from ../../chrome/browser/ui/webui/interstitials/interstitial_ui.cc:12:0:
../../chrome/browser/safe_browsing/safe_browsing_blocking_page.h:143:16:
error: ‘safe_browsing::SafeBrowsingBlockingPageTest_MalwareReportsToggling_Test’
is already a friend of ‘safe_browsing::SafeBrowsingBlockingPage’ [-Werror]
   FRIEND_TEST_ALL_PREFIXES(SafeBrowsingBlockingPageTest,

../../chrome/browser/safe_browsing/safe_browsing_blocking_page.h:143:87:
error: ‘safe_browsing::SafeBrowsingBlockingPageTest_DISABLED_MalwareReportsToggling_Test’
is already a friend of ‘safe_browsing::SafeBrowsingBlockingPage’ [-Werror]
   FRIEND_TEST_ALL_PREFIXES(SafeBrowsingBlockingPageTest,

../../chrome/browser/safe_browsing/safe_browsing_blocking_page.h:143:167:
error: ‘safe_browsing::SafeBrowsingBlockingPageTest_FLAKY_MalwareReportsToggling_Test’
is already a friend of ‘safe_browsing::SafeBrowsingBlockingPage’ [-Werror]
   FRIEND_TEST_ALL_PREFIXES(SafeBrowsingBlockingPageTest,

Android build had no issues.

BUG=NONE
TESTS=NONE

Review URL: https://codereview.chromium.org/1551583002

Cr-Commit-Position: refs/heads/master@{#367058}

chrome/browser/safe_browsing/safe_browsing_blocking_page.h

@@ -138,11 +138,6 @@ class SafeBrowsingBlockingPage : public SecurityInterstitialPage {
   // milliseconds), in order to get data from the blocked resource itself.
   int64_t malware_details_proceed_delay_ms_;
 
-  FRIEND_TEST_ALL_PREFIXES(SafeBrowsingBlockingPageTest,
-      MalwareReportsTransitionDisabled);
-  FRIEND_TEST_ALL_PREFIXES(SafeBrowsingBlockingPageTest,
-      MalwareReportsToggling);
-
   // Checks if we should even show the threat details option. For example, we
   // don't show it in incognito mode.
   bool CanShowThreatDetailsOption();