Revert "Disable flaky testSafeBrowsingOnSafeBrowsingHitProceed"

This reverts commit cf978e3.

Reason for revert: not more flaky than the other ones. https://bugs.chromium.org/p/chromium/issues/detail?id=821697#c17

Original change's description:
> Disable flaky testSafeBrowsingOnSafeBrowsingHitProceed
> 
> TBR=ntfschr
> 
> Bug: 821697
> Change-Id: I61515e735a542cf94dcb00c50263ea512d66fcea
> Reviewed-on: https://chromium-review.googlesource.com/963081
> Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
> Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#543146}

TBR=crouleau@chromium.org,ntfschr@chromium.org

Change-Id: I141561d5448a77c0dc12a91032850c9dd2dc2e1c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 821697
Reviewed-on: https://chromium-review.googlesource.com/963230
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543180}

android_webview/javatests/src/org/chromium/android_webview/test/SafeBrowsingTest.java

@@ -778,7 +778,6 @@ public void testSafeBrowsingOnSafeBrowsingHitShowInterstitial() throws Throwable
     @Test
     @SmallTest
     @Feature({"AndroidWebView"})
-    @DisabledTest
     public void testSafeBrowsingOnSafeBrowsingHitProceed() throws Throwable {
         mContentsClient.setSafeBrowsingAction(SafeBrowsingAction.PROCEED);