Reland "Fix emission of AtkValue property change signal"

This version checks at runtime for atk_value_set_value during testing.
This should allow the change to work on bots running trusty.

Original commit message:

> The introduction of text-change signals for the omnibox included a
> regression that prevented the emission of AtkValue property change
> signals. Fix this error and also add an implementation of
> atk_value_set_value. The implementation is used in a test to verify the
> correct behavior.
>
> The fix is that we correct the misuse of a logical operator and now
> always try to emit AtkValue property change events when receiving the
> kValueChanged event in AXPlatformNodeAuraLinux.

Bug: 1015387
Change-Id: I486b44f9d0f212d951487bdc9f953401a94f9dff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1876850
Commit-Queue: Martin Robinson <mrobinson@igalia.com>
Reviewed-by: Joanmarie Diggs <jdiggs@igalia.com>
Cr-Commit-Position: refs/heads/master@{#709023}

ui/accessibility/platform/ax_platform_node_auralinux.cc

@@ -764,11 +764,31 @@ void GetMinimumIncrement(AtkValue* atk_value, GValue* value) {
                                  value);
 }
 
+#if defined(ATK_212)
+void SetValue(AtkValue* atk_value, const double new_value) {
+  g_return_if_fail(ATK_VALUE(atk_value));
+
+  AtkObject* atk_object = ATK_OBJECT(atk_value);
+  AXPlatformNodeAuraLinux* obj = AtkObjectToAXPlatformNodeAuraLinux(atk_object);
+  if (!obj)
+    return;
+
+  AXActionData data;
+  data.action = ax::mojom::Action::kSetValue;
+  data.value = base::NumberToString(new_value);
+  obj->GetDelegate()->AccessibilityPerformAction(data);
+}
+#endif  // defined(ATK_212)
+
 void Init(AtkValueIface* iface) {
   iface->get_current_value = GetCurrentValue;
   iface->get_maximum_value = GetMaximumValue;
   iface->get_minimum_value = GetMinimumValue;
   iface->get_minimum_increment = GetMinimumIncrement;
+
+#if defined(ATK_212)
+  iface->set_value = SetValue;
+#endif  // defined(ATK_212)
 }
 
 const GInterfaceInfo Info = {reinterpret_cast<GInterfaceInitFunc>(Init),
@@ -3408,10 +3428,8 @@ void AXPlatformNodeAuraLinux::OnValueChanged() {
   // If this is a non-web-content text entry, then we need to trigger text
   // change signals when the value changes. This is handled by browser
   // accessibility for web content.
-  if (IsPlainTextField() || !GetDelegate()->IsWebContent()) {
+  if (IsPlainTextField() && !GetDelegate()->IsWebContent())
     UpdateHypertext();
-    return;
-  }
 
   if (!IsRangeValueSupported(GetData()))
     return;

ui/accessibility/platform/ax_platform_node_auralinux_unittest.cc

@@ -973,6 +973,65 @@ TEST_F(AXPlatformNodeAuraLinuxTest, TestAtkValueGetMinimumIncrement) {
   g_object_unref(root_obj);
 }
 
+#if ATK_CHECK_VERSION(2, 12, 0)
+typedef bool (*SetValueFunction)(AtkValue* component, double value);
+TEST_F(AXPlatformNodeAuraLinuxTest, TestAtkValueChangedSignal) {
+  // There's a chance we may be compiled with a newer version of ATK and then
+  // run with an older one, so we need to do a runtime check for this method
+  // that is available in ATK 2.12 instead of linking directly.
+  SetValueFunction set_value = reinterpret_cast<SetValueFunction>(
+      dlsym(RTLD_DEFAULT, "atk_value_set_value"));
+  if (!set_value) {
+    LOG(WARNING) << "Skipping TestAtkValueChangedSignal"
+                    " because ATK version < 2.12 detected.";
+    return;
+  }
+
+  AXNodeData root;
+  root.id = 1;
+  root.role = ax::mojom::Role::kSlider;
+  root.AddFloatAttribute(ax::mojom::FloatAttribute::kMaxValueForRange, 5.0);
+  Init(root);
+
+  AtkObject* root_object(GetRootAtkObject());
+  ASSERT_TRUE(ATK_IS_OBJECT(root_object));
+  ASSERT_TRUE(ATK_IS_VALUE(root_object));
+  g_object_ref(root_object);
+
+  bool saw_value_change = false;
+  g_signal_connect(
+      root_object, "property-change::accessible-value",
+      G_CALLBACK(+[](AtkObject*, void* property, bool* saw_value_change) {
+        *saw_value_change = true;
+      }),
+      &saw_value_change);
+
+  set_value(ATK_VALUE(root_object), 24.0);
+  GetRootPlatformNode()->NotifyAccessibilityEvent(
+      ax::mojom::Event::kValueChanged);
+
+  GValue current_value = G_VALUE_INIT;
+  atk_value_get_current_value(ATK_VALUE(root_object), &current_value);
+  EXPECT_EQ(G_TYPE_FLOAT, G_VALUE_TYPE(&current_value));
+  EXPECT_EQ(24.0, g_value_get_float(&current_value));
+  EXPECT_TRUE(saw_value_change);
+
+  saw_value_change = false;
+  set_value(ATK_VALUE(root_object), 100.0);
+  GetRootPlatformNode()->NotifyAccessibilityEvent(
+      ax::mojom::Event::kValueChanged);
+
+  g_value_unset(&current_value);
+  atk_value_get_current_value(ATK_VALUE(root_object), &current_value);
+  EXPECT_EQ(G_TYPE_FLOAT, G_VALUE_TYPE(&current_value));
+  EXPECT_EQ(100.0, g_value_get_float(&current_value));
+  EXPECT_TRUE(saw_value_change);
+
+  g_value_unset(&current_value);
+  g_object_unref(root_object);
+}
+#endif  // ATK_CHECK_VERSION(2, 12, 0)
+
 //
 // AtkHyperlinkImpl interface
 //