[chrome:accessibility] Observe AXEvents

Observe AXEvents received by the RenderFrameHost. Log them in the
the accessibility events recorder, which records events from the
OS.

chrome: accessibility page, intermixed with the events recorded by
Bug: 785493
Change-Id: I7a72f786567c1f661de9f0945c01dc4d46789e72
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900209
Commit-Queue: Abigail Klein <abigailbklein@google.com>
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713515}

chrome/browser/accessibility/accessibility_ui.cc

@@ -26,6 +26,7 @@
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/accessibility_tree_formatter.h"
+#include "content/public/browser/ax_event_notification_details.h"
 #include "content/public/browser/browser_accessibility_state.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/favicon_status.h"
@@ -348,11 +349,25 @@ AccessibilityUI::AccessibilityUI(content::WebUI* web_ui)
   web_ui->AddMessageHandler(std::make_unique<AccessibilityUIMessageHandler>());
 }
 
-AccessibilityUI::~AccessibilityUI() {}
+AccessibilityUI::~AccessibilityUI() = default;
 
-AccessibilityUIMessageHandler::AccessibilityUIMessageHandler() {}
+AccessibilityUIObserver::AccessibilityUIObserver(
+    content::WebContents* web_contents,
+    std::vector<std::string>* event_logs)
+    : content::WebContentsObserver(web_contents), event_logs_(event_logs) {}
 
-AccessibilityUIMessageHandler::~AccessibilityUIMessageHandler() {}
+AccessibilityUIObserver::~AccessibilityUIObserver() = default;
+
+void AccessibilityUIObserver::AccessibilityEventReceived(
+    const content::AXEventNotificationDetails& details) {
+  for (const ui::AXEvent event : details.events) {
+    event_logs_->push_back(event.ToString());
+  }
+}
+
+AccessibilityUIMessageHandler::AccessibilityUIMessageHandler() = default;
+
+AccessibilityUIMessageHandler::~AccessibilityUIMessageHandler() = default;
 
 void AccessibilityUIMessageHandler::RegisterMessages() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
@@ -649,11 +664,15 @@ void AccessibilityUIMessageHandler::RequestAccessibilityEvents(
         base::BindRepeating(&AccessibilityUIMessageHandler::Callback,
                             base::Unretained(this)),
         true);
+    observer_ =
+        std::make_unique<AccessibilityUIObserver>(web_contents, &event_logs_);
   } else {
     web_contents->RecordAccessibilityEvents(
         base::BindRepeating(&AccessibilityUIMessageHandler::Callback,
                             base::Unretained(this)),
         false);
+    observer_.release();
+
     std::string event_logs_str;
     for (std::string log : event_logs_) {
       event_logs_str += log;

chrome/browser/accessibility/accessibility_ui.h

@@ -5,7 +5,12 @@
 #ifndef CHROME_BROWSER_ACCESSIBILITY_ACCESSIBILITY_UI_H_
 #define CHROME_BROWSER_ACCESSIBILITY_ACCESSIBILITY_UI_H_
 
+#include <memory>
+#include <string>
+#include <vector>
+
 #include "base/macros.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "content/public/browser/web_ui_data_source.h"
 #include "content/public/browser/web_ui_message_handler.h"
@@ -14,16 +19,36 @@ namespace base {
 class ListValue;
 }  // namespace base
 
+namespace content {
+struct AXEventNotificationDetails;
+}  // namespace content
+
 namespace user_prefs {
 class PrefRegistrySyncable;
 }  // namespace user_prefs
 
+// Controls the accessibility web UI page.
 class AccessibilityUI : public content::WebUIController {
  public:
   explicit AccessibilityUI(content::WebUI* web_ui);
   ~AccessibilityUI() override;
 };
 
+// Observes accessibility events from web contents.
+class AccessibilityUIObserver : public content::WebContentsObserver {
+ public:
+  AccessibilityUIObserver(content::WebContents* web_contents,
+                          std::vector<std::string>* event_logs);
+  ~AccessibilityUIObserver() override;
+
+  void AccessibilityEventReceived(
+      const content::AXEventNotificationDetails& details) override;
+
+ private:
+  std::vector<std::string>* event_logs_;
+};
+
+// Manages messages sent from accessibility.js via json.
 class AccessibilityUIMessageHandler : public content::WebUIMessageHandler {
  public:
   AccessibilityUIMessageHandler();
@@ -35,6 +60,7 @@ class AccessibilityUIMessageHandler : public content::WebUIMessageHandler {
 
  private:
   std::vector<std::string> event_logs_;
+  std::unique_ptr<AccessibilityUIObserver> observer_;
 
   void ToggleAccessibility(const base::ListValue* args);
   void SetGlobalFlag(const base::ListValue* args);