Improve Android accessible hit testing.

content/browser/accessibility/browser_accessibility_android.cc

Index: content/browser/accessibility/browser_accessibility_android.cc
diff --git a/content/browser/accessibility/browser_accessibility_android.cc b/content/browser/accessibility/browser_accessibility_android.cc
index c3a50a485617adcb7004ffd0b78f4958a4b0279e..b0fdd15733f2eeb5abe1999c60577eafd0d80db8 100644
--- a/content/browser/accessibility/browser_accessibility_android.cc
+++ b/content/browser/accessibility/browser_accessibility_android.cc
@@ -277,6 +277,42 @@ bool BrowserAccessibilityAndroid::IsVisibleToUser() const {
   return !HasState(ui::AX_STATE_INVISIBLE);
 }
 
+bool BrowserAccessibilityAndroid::IsInterestingOnAndroid() const {
+  // Focusable nodes are always interesting. Note that IsFocusable()
+  // already skips over things like iframes and child frames that are
+  // technically focusable but shouldn't be exposed as focusable on Android.
+  if (IsFocusable())
+    return true;
+
+  // If it's not focusable but has a control role, then it's interesting.
+  if (IsControl())
+    return true;
+
+  // Otherwise, the interesting nodes are leaf nodes with text.
+  return PlatformIsLeaf() && !GetText().empty();
+}
+
+const BrowserAccessibilityAndroid*
+    BrowserAccessibilityAndroid::GetInterestingChild() const {

[aboxhall, 2016/10/18 21:03:24]

Trying to think of a less confusing name for this - it's not necessarily a
child, not necessarily a direct child, and doesn't necessarily return an
interesting child even if one exists.

Maybe something like "SoleInterestingNodeForSubtree"?

[dmazzoni, 2016/10/18 22:09:36]

Good idea, I changed it to GetSoleInterestingDescendant()

+  if (IsInterestingOnAndroid())
+    return this;
+
+  const BrowserAccessibilityAndroid* interesting_child = nullptr;
+  for (uint32_t i = 0; i < PlatformChildCount(); ++i) {
+    const BrowserAccessibilityAndroid* result =
+        static_cast<const BrowserAccessibilityAndroid*>(PlatformGetChild(i))->
+            GetInterestingChild();
+    if (result && interesting_child) {

[aboxhall, 2016/10/18 21:03:24]

Maybe s/result/interesting_child/ and
s/interesting_child/sole_interesting_child/ or similar?

[dmazzoni, 2016/10/18 22:09:36]

Done.

+      // If there are two interesting children, return nullptr
+      return nullptr;
+    } else if (result) {
+      interesting_child = result;
+    }
+  }
+
+  return interesting_child;
+}
+
 bool BrowserAccessibilityAndroid::CanOpenPopup() const {
   return HasState(ui::AX_STATE_HASPOPUP);
 }