Do not block a11y events on trimmed Android text nodes

Do not suppress events on descendants of leaf nodes on Android, otherwise
necessary events are not fired. This is because Android treats a lot more
nodes as leaves.

Bug: 907866
Change-Id: If93d55747249d9084c57a091647f8d4860df6d3c
Reviewed-on: https://chromium-review.googlesource.com/c/1351494Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611260}

content/browser/accessibility/browser_accessibility.cc

@@ -73,6 +73,11 @@ bool BrowserAccessibility::PlatformIsLeaf() const {
   }
 }
 
+bool BrowserAccessibility::CanFireEvents() const {
+  // Allow events unless this object would be trimmed away.
+  return !PlatformIsChildOfLeaf();
+}
+
 uint32_t BrowserAccessibility::PlatformChildCount() const {
   if (HasStringAttribute(ax::mojom::StringAttribute::kChildTreeId)) {
     AXTreeID child_tree_id = AXTreeID::FromString(

content/browser/accessibility/browser_accessibility.h

@@ -114,6 +114,9 @@ class CONTENT_EXPORT BrowserAccessibility : public ui::AXPlatformNodeDelegate {
   // that might send notifications.
   virtual bool PlatformIsLeaf() const;
 
+  // Returns true if this object can fire events.
+  virtual bool CanFireEvents() const;
+
   // Returns the number of children of this object, or 0 if PlatformIsLeaf()
   // returns true.
   virtual uint32_t PlatformChildCount() const;

content/browser/accessibility/browser_accessibility_android.cc

@@ -209,6 +209,10 @@ bool BrowserAccessibilityAndroid::PlatformIsLeaf() const {
   return false;
 }
 
+bool BrowserAccessibilityAndroid::CanFireEvents() const {
+  return true;
+}
+
 bool BrowserAccessibilityAndroid::IsCheckable() const {
   return HasIntAttribute(ax::mojom::IntAttribute::kCheckedState);
 }

content/browser/accessibility/browser_accessibility_android.h

@@ -27,6 +27,8 @@ class CONTENT_EXPORT BrowserAccessibilityAndroid : public BrowserAccessibility {
   base::string16 GetValue() const override;
 
   bool PlatformIsLeaf() const override;
+  // Android needs events even on objects that are trimmed away.
+  bool CanFireEvents() const override;
 
   bool IsCheckable() const;
   bool IsChecked() const;

content/browser/accessibility/browser_accessibility_manager.cc

@@ -376,7 +376,7 @@ void BrowserAccessibilityManager::OnAccessibilityEvents(
   // Fire any events related to changes to the tree.
   for (auto targeted_event : *this) {
     BrowserAccessibility* event_target = GetFromAXNode(targeted_event.node);
-    if (!event_target || event_target->PlatformIsChildOfLeaf())
+    if (!event_target || !event_target->CanFireEvents())
       continue;
 
     FireGeneratedEvent(targeted_event.event_params.event, event_target);
@@ -389,7 +389,7 @@ void BrowserAccessibilityManager::OnAccessibilityEvents(
 
     // Fire the native event.
     BrowserAccessibility* event_target = GetFromID(event.id);
-    if (!event_target || event_target->PlatformIsChildOfLeaf())
+    if (!event_target || !event_target->CanFireEvents())
       return;
 
     if (event.event_type == ax::mojom::Event::kHover)

content/browser/accessibility/browser_accessibility_manager_win.cc

@@ -191,7 +191,7 @@ void BrowserAccessibilityManagerWin::FireGeneratedEvent(
 void BrowserAccessibilityManagerWin::FireWinAccessibilityEvent(
     LONG win_event_type,
     BrowserAccessibility* node) {
-  if (node->PlatformIsChildOfLeaf())
+  if (!node->CanFireEvents())
     return;
 
   // If there's no root delegate, this may be a new frame that hasn't

content/browser/accessibility/browser_accessibility_unittest.cc

+// Copyright (c) 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/accessibility/browser_accessibility.h"
+
+#include "build/build_config.h"
+#include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+class BrowserAccessibilityTest : public testing::Test {
+ public:
+  BrowserAccessibilityTest();
+  ~BrowserAccessibilityTest() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityTest);
+};
+
+BrowserAccessibilityTest::BrowserAccessibilityTest() {}
+
+BrowserAccessibilityTest::~BrowserAccessibilityTest() {}
+
+TEST_F(BrowserAccessibilityTest, TestCanFireEvents) {
+  ui::AXNodeData text1;
+  text1.id = 111;
+  text1.role = ax::mojom::Role::kStaticText;
+  text1.SetName("One two three.");
+
+  ui::AXNodeData para1;
+  para1.id = 11;
+  para1.role = ax::mojom::Role::kParagraph;
+  para1.child_ids.push_back(text1.id);
+
+  ui::AXNodeData root;
+  root.id = 1;
+  root.role = ax::mojom::Role::kRootWebArea;
+  root.child_ids.push_back(para1.id);
+
+  std::unique_ptr<BrowserAccessibilityManager> manager(
+      BrowserAccessibilityManager::Create(MakeAXTreeUpdate(root, para1, text1),
+                                          nullptr,
+                                          new BrowserAccessibilityFactory()));
+
+  BrowserAccessibility* root_obj = manager->GetRoot();
+  EXPECT_FALSE(root_obj->PlatformIsLeaf());
+  EXPECT_TRUE(root_obj->CanFireEvents());
+
+  BrowserAccessibility* para_obj = root_obj->PlatformGetChild(0);
+  EXPECT_TRUE(para_obj->CanFireEvents());
+#if defined(OS_ANDROID)
+  EXPECT_TRUE(para_obj->PlatformIsLeaf());
+#else
+  EXPECT_FALSE(para_obj->PlatformIsLeaf());
+#endif
+
+  BrowserAccessibility* text_obj = manager->GetFromID(111);
+  EXPECT_TRUE(text_obj->PlatformIsLeaf());
+  EXPECT_TRUE(text_obj->CanFireEvents());
+
+  manager.reset();
+}
+
+}  // namespace content

content/test/BUILD.gn

@@ -1298,6 +1298,7 @@ test("content_unittests") {
   sources = [
     "../browser/accessibility/browser_accessibility_mac_unittest.mm",
     "../browser/accessibility/browser_accessibility_manager_unittest.cc",
+    "../browser/accessibility/browser_accessibility_unittest.cc",
     "../browser/accessibility/browser_accessibility_win_unittest.cc",
     "../browser/accessibility/one_shot_accessibility_tree_search_unittest.cc",
     "../browser/appcache/appcache_database_unittest.cc",