Fix a few NetErrorAutoReloader browser tests

The disabled tests cover the effect of a WebContents' visibility on
its auto-reload behavior.

It turns out that visibility of WebContents within content_shell
behaves somewhat unexpectedly -- at least on Mac -- resulting
in the WebContents non-deterministically becoming visible during a
navigation, despite being explicitly hidden by test logic prior to
the navigation.

In order to avoid the resulting flakiness, this rearranges the test
logic so that forced visibility changes are imposed *after*
the relevant navigation rather than before it.

Fixed: 1110259
Change-Id: I38ab9d22a225018a8c5a1762cac15af45bf846e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324163Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#792470}

components/error_page/content/browser/net_error_auto_reloader_browsertest.cc

@@ -495,29 +495,30 @@ IN_PROC_BROWSER_TEST_F(NetErrorAutoReloaderBrowserTest,
 }
 
 // Auto-reload is not scheduled when the WebContents are hidden.
-// TODO(crbug/1110259): The test is disabled due to flakiness on multiple platforms.
 IN_PROC_BROWSER_TEST_F(NetErrorAutoReloaderBrowserTest,
-                       DISABLED_NoAutoReloadWhenContentsHidden) {
-  shell()->web_contents()->WasHidden();
-
-  // This would normally schedule an auto-reload, but we're offline.
+                       NoAutoReloadWhenContentsHidden) {
   NetErrorUrlInterceptor interceptor(GetTestUrl(), net::ERR_CONNECTION_RESET);
   EXPECT_FALSE(NavigateMainFrame(GetTestUrl()));
+  EXPECT_EQ(GetDelayForReloadCount(0), GetCurrentAutoReloadDelay());
+
+  // Hiding the contents cancels the scheduled auto-reload.
+  shell()->web_contents()->WasHidden();
   EXPECT_EQ(base::nullopt, GetCurrentAutoReloadDelay());
 }
 
 // If the WebContents becomes visible while sitting at an error page that
 // supports auto-reload, a new auto-reload task should be scheduled.
-// TODO(crbug/1110259): The test is disabled due to flakiness on multiple platforms.
 IN_PROC_BROWSER_TEST_F(NetErrorAutoReloaderBrowserTest,
-                       DISABLED_AutoReloadWhenContentsBecomeVisible) {
-  shell()->web_contents()->WasHidden();
-
-  // This would normally schedule an auto-reload, but we're offline.
+                       AutoReloadWhenContentsBecomeVisible) {
   NetErrorUrlInterceptor interceptor(GetTestUrl(), net::ERR_CONNECTION_RESET);
   EXPECT_FALSE(NavigateMainFrame(GetTestUrl()));
+  EXPECT_EQ(GetDelayForReloadCount(0), GetCurrentAutoReloadDelay());
+
+  // Hiding the contents cancels the scheduled auto-reload.
+  shell()->web_contents()->WasHidden();
   EXPECT_EQ(base::nullopt, GetCurrentAutoReloadDelay());
 
+  // Becoming visible again reschedules auto-reload.
   shell()->web_contents()->WasShown();
   EXPECT_EQ(GetDelayForReloadCount(0), GetCurrentAutoReloadDelay());
 }