Implement Android accessible hit testing using an IPC to the renderer process.

content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java

Index: content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java b/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
index 63deca865b67ba0a772f2fce6225320f780b215b..6f4723369ce1bc00f9f45a8435c8beebc875c66f 100644
--- a/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
+++ b/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
@@ -248,18 +248,12 @@ public class BrowserAccessibilityManager {
         float y = event.getY();
 
         // Convert to CSS coordinates.
-        int cssX = (int) (mRenderCoordinates.fromPixToLocalCss(x) +
-                          mRenderCoordinates.getScrollX());
-        int cssY = (int) (mRenderCoordinates.fromPixToLocalCss(y) +
-                          mRenderCoordinates.getScrollY());
-        int id = nativeHitTest(mNativeObj, cssX, cssY);
-        if (mLastHoverId != id) {
-            // Always send the ENTER and then the EXIT event, to match a standard Android View.
-            sendAccessibilityEvent(id, AccessibilityEvent.TYPE_VIEW_HOVER_ENTER);
-            sendAccessibilityEvent(mLastHoverId, AccessibilityEvent.TYPE_VIEW_HOVER_EXIT);
-            mLastHoverId = id;
-        }
+        int cssX = (int) (mRenderCoordinates.fromPixToLocalCss(x));
+        int cssY = (int) (mRenderCoordinates.fromPixToLocalCss(y));
 
+        // This sends an IPC to the render process to do the hit testing.
+        // The response is handled by handleHover.
+        nativeHitTest(mNativeObj, cssX, cssY);

[Peter Lundblad, 2014/05/19 16:58:44]

Do we get lots of these events if a user just holds his finger
on the screen (you never hold your finger exactly still)?  Could the render
process
be flooded if that's the case?  Don't know if this actually is an issue, just
making sure it's been considered.

         return true;
     }
 
@@ -441,6 +435,16 @@ public class BrowserAccessibilityManager {
     }
 
     @CalledByNative
+    private void handleHover(int id) {
+        if (mLastHoverId == id) return;
+
+        // Always send the ENTER and then the EXIT event, to match a standard Android View.
+        sendAccessibilityEvent(id, AccessibilityEvent.TYPE_VIEW_HOVER_ENTER);
+        sendAccessibilityEvent(mLastHoverId, AccessibilityEvent.TYPE_VIEW_HOVER_EXIT);
+        mLastHoverId = id;
+    }
+
+    @CalledByNative
     private void announceLiveRegionText(String text) {
         mView.announceForAccessibility(text);
     }
@@ -682,7 +686,7 @@ public class BrowserAccessibilityManager {
 
     private native int nativeGetRootId(long nativeBrowserAccessibilityManagerAndroid);
     private native boolean nativeIsNodeValid(long nativeBrowserAccessibilityManagerAndroid, int id);
-    private native int nativeHitTest(long nativeBrowserAccessibilityManagerAndroid, int x, int y);
+    private native void nativeHitTest(long nativeBrowserAccessibilityManagerAndroid, int x, int y);
     private native boolean nativePopulateAccessibilityNodeInfo(
         long nativeBrowserAccessibilityManagerAndroid, AccessibilityNodeInfo info, int id);
     private native boolean nativePopulateAccessibilityEvent(