Fix ForceEnabledOriginTrials_MainPage on Site Isolation Android FYI bot.

The test
ForceEnabledOriginTrialsBrowserTest.ForceEnabledOriginTrials_MainPage
was failing on Site Isolation Android FYI bot, because the "/1" variety
of the test expects to run with with site isolation disabled, and
assumes that there will only be one renderer process in that case.  The
FYI bot runs with --site-per-process, which turns a cross-site iframe on
the test page into an OOPIF even in the presence of
--disable-site-isolation-trials, adding another renderer process. Adjust
test expectations accordingly.

Bug: 1137881
Change-Id: I45c0dd18a47c0ce58c3581daa8412ce8bf042a24
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2468340Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org>
Commit-Queue: Alex Moshchuk <alexmos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816716}

content/browser/origin_trials/origin_trials_browsertest.cc

@@ -188,8 +188,10 @@ IN_PROC_BROWSER_TEST_P(ForceEnabledOriginTrialsBrowserTest,
   EXPECT_FALSE(HasTrialEnabled(GetFrameByName("same-origin")));
   EXPECT_FALSE(HasTrialEnabled(GetFrameByName("cross-origin")));
 
-  if (disable_site_isolation_)
-    ASSERT_EQ(1, RenderProcessHost::GetCurrentRenderProcessCountForTesting());
+  // With site isolation, the cross-site iframe on |main_url_| will get its own
+  // process.  Otherwise, we'll only get one main frame process.
+  ASSERT_EQ(AreAllSitesIsolatedForTesting() ? 2 : 1,
+            RenderProcessHost::GetCurrentRenderProcessCountForTesting());
 
   // OT does not persist when we navigated away.
   NavigateViaRenderer(shell()->web_contents(),