[ios] Update wide pdf test for iOS12.

Swiping up on a short/wide pdf no longer hides the toolbar.

Also disable synchronization for testSmallWidePDFScroll on iOS12,
but it's likely something larger is going on.

Bug: 852393
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Iab556064447cfe54cb498678d192a45f36b55a1a
Reviewed-on: https://chromium-review.googlesource.com/1100337
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567846}

ios/chrome/browser/ui/fullscreen/fullscreen_egtest.mm

@@ -124,6 +124,14 @@ void AssertURLIs(const GURL& expectedURL) {
       "http://ios/testing/data/http_server_files/single_page_wide.pdf");
   [ChromeEarlGrey loadURL:URL];
 
+  // TODO(crbug.com/852393): Investigate why synchronization isn't working.  Is
+  // an animation going on forever?
+  if (@available(iOS 12, *)) {
+    [[GREYConfiguration sharedInstance]
+            setValue:@NO
+        forConfigKey:kGREYConfigKeySynchronizationEnabled];
+  }
+
   // Test that the toolbar is still visible after a user swipes down.
   [[EarlGrey
       selectElementWithMatcher:WebViewScrollView(
@@ -131,9 +139,23 @@ void AssertURLIs(const GURL& expectedURL) {
       performAction:grey_swipeFastInDirection(kGREYDirectionDown)];
   [ChromeEarlGreyUI waitForToolbarVisible:YES];
 
-  // Test that the toolbar is no longer visible after a user swipes up.
-  HideToolbarUsingUI();
-  [ChromeEarlGreyUI waitForToolbarVisible:NO];
+  if (base::ios::IsRunningOnIOS12OrLater()) {
+    // Test that the toolbar is still visible even after attempting to hide it
+    // on swipe up.
+    HideToolbarUsingUI();
+    [ChromeEarlGreyUI waitForToolbarVisible:YES];
+  } else {
+    // Test that the toolbar is no longer visible after a user swipes up.
+    HideToolbarUsingUI();
+    [ChromeEarlGreyUI waitForToolbarVisible:NO];
+  }
+
+  // Reenable synchronization.
+  if (@available(iOS 12, *)) {
+    [[GREYConfiguration sharedInstance]
+            setValue:@YES
+        forConfigKey:kGREYConfigKeySynchronizationEnabled];
+  }
 }
 
 // Verifies that the toolbar properly appears/disappears when scrolling up/down