Fixes disappearing text in Find in page toolbar in slide over.

ios/chrome/browser/find_in_page/find_in_page_controller.mm

Index: ios/chrome/browser/find_in_page/find_in_page_controller.mm
diff --git a/ios/chrome/browser/find_in_page/find_in_page_controller.mm b/ios/chrome/browser/find_in_page/find_in_page_controller.mm
index d6da2ebe18d896ff06e6e3832f342ef4e73bb795..81528336a4c3c42ba1b3f754c72b6a0bb59cd14b 100644
--- a/ios/chrome/browser/find_in_page/find_in_page_controller.mm
+++ b/ios/chrome/browser/find_in_page/find_in_page_controller.mm
@@ -290,6 +290,12 @@ const NSTimeInterval kRecurringPumpDelay = .01;
 }
 
 - (void)restoreSearchTerm {
+  // Pasteboards always return nil in background:
+  if ([[UIApplication sharedApplication] applicationState] !=
+      UIApplicationStateActive) {
+    return;
+  }
+
   NSString* term = [self findPasteboard].string;
   [[self findInPageModel] updateQuery:(term ? term : @"") matches:0];
 }