Add a testing switch to override the query for other forms of browsing history

chrome/browser/ui/webui/history_ui.h

Index: chrome/browser/ui/webui/history_ui.h
diff --git a/chrome/browser/ui/webui/history_ui.h b/chrome/browser/ui/webui/history_ui.h
index 0b576bc8fb213b644555f254367b1318ed9e83a3..9e9bc36fda559e29611d2694976198948a48a349 100644
--- a/chrome/browser/ui/webui/history_ui.h
+++ b/chrome/browser/ui/webui/history_ui.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_UI_WEBUI_HISTORY_UI_H_
 
 #include "base/macros.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
@@ -13,7 +14,8 @@ namespace base {
 class RefCountedMemory;
 }
 
-class HistoryUI : public content::WebUIController {
+class HistoryUI : public content::WebUIController,
+                  public content::WebContentsObserver {
  public:
   explicit HistoryUI(content::WebUI* web_ui);
   ~HistoryUI() override;
@@ -21,6 +23,9 @@ class HistoryUI : public content::WebUIController {
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
 
+  // WebContentsObserver implementation.
+  void DidStopLoading() override;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(HistoryUI);
 };