bfcache: Update test. Clear in-page memory cache correctly.

To clear the in-memory cache, the test was relying on a cross-process
navigation. This is not enough, because the old page can be kept in the
back-forward cache.

This patch disables the back-forward cache for the old page.

Bug: 999849
Change-Id: I7f2587d0bc25a349c74c8a68599e74db4eb8e318
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1863296
Commit-Queue: Mohamed Abdelhalim <zetamoo@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706466}

content/browser/web_contents/web_contents_impl_browsertest.cc

@@ -31,6 +31,7 @@
 #include "content/browser/web_contents/web_contents_view.h"
 #include "content/common/frame_messages.h"
 #include "content/common/unfreezable_frame_messages.h"
+#include "content/public/browser/back_forward_cache.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/file_select_listener.h"
 #include "content/public/browser/invalidate_type.h"
@@ -1052,11 +1053,13 @@ class WebContentsSplitCacheBrowserTest : public WebContentsImplBrowserTest {
                               const GURL& worker) {
     DCHECK(url.is_valid());
 
-    // Do a cross-process navigation to clear the in-memory cache.
-    // We assume that we don't start this call from "chrome://gpu", as
-    // otherwise it won't be a cross-process navigation. We are relying
-    // on this navigation to discard the old process.
-    EXPECT_TRUE(NavigateToURL(shell(), GetWebUIURL("gpu")));
+    // Clear the in-memory cache held by the current process:
+    // 1) Prevent the old page from entering the back-forward cache. Otherwise
+    //    the old process will be kept alive, because it is still being used.
+    // 2) Navigate to a WebUI URL, which uses a new process.
+    BackForwardCache::DisableForRenderFrameHost(
+        shell()->web_contents()->GetMainFrame(), "test");
+    EXPECT_TRUE(NavigateToURL(shell(), GetWebUIURL(kChromeUIGpuHost)));
 
     // Observe network requests.
     ResourceLoadObserver observer(shell());

testing/buildbot/filters/bfcache.content_browsertests.filter

@@ -55,11 +55,6 @@
 # happen when the BackForwardCache is used to store the old document.
 -RenderFrameHostManagerTest.RenderViewInitAfterNewProxyAndProcessKill
 
-# FATAL:casting.h Security DCHECK failed: IsA<Derived>(from).
-# In content::RenderFrameProxy::OnSetFrameOwnerProperties()
-# https://crbug.com/999849
--WebContentsSplitCacheWithFrameOriginBrowserTest.SplitCache*
-
 # Histogram "PrefetchedSignedExchangeCache.Count" is recorded when the document
 # in the RenderFrameHost is replaced, or when the RenderFrameHost is deleted.
 # With the BackForwardCache, the RenderFrameHost is not deleted, so the