Introduce ViewRoot to forward input/view events to native

ui/android/view_android.h

Index: ui/android/view_android.h
diff --git a/ui/android/view_android.h b/ui/android/view_android.h
index 607a1acc72ae4dad10cfc8216cd5d76831b33c6f..6a728c6a8d506f30fade73a7e309eb55831874bf 100644
--- a/ui/android/view_android.h
+++ b/ui/android/view_android.h
@@ -18,6 +18,7 @@ class Layer;
 
 namespace ui {
 
+class ViewClient;
 class WindowAndroid;
 
 // A simple container for a UI layer.
@@ -54,17 +55,20 @@ class UI_ANDROID_EXPORT ViewAndroid {
     // Default copy/assign disabled by move constructor.
   };
 
-  // A ViewAndroid may have its own delegate or otherwise will
-  // use the next available parent's delegate.
-  ViewAndroid(const base::android::JavaRef<jobject>& delegate);
+  explicit ViewAndroid(ViewClient* client);
 
   ViewAndroid();
+
   virtual ~ViewAndroid();
 
   // Returns the window at the root of this hierarchy, or |null|
   // if disconnected.
   virtual WindowAndroid* GetWindowAndroid() const;
 
+  // Returns |EventHandler| associated with the current ViewAndroid.
+  // Create one if not present.
+  virtual base::android::ScopedJavaLocalRef<jobject> GetEventHandler();

[boliu, 2016/12/08 05:01:06]

shouldn't be virtual

[Jinsuk Kim, 2016/12/13 23:20:38]

Done.

+
   // Used to return and set the layer for this view. May be |null|.
   cc::Layer* GetLayer() const;
   void SetLayer(scoped_refptr<cc::Layer> layer);
@@ -84,21 +88,52 @@ class UI_ANDROID_EXPORT ViewAndroid {
   void SetAnchorRect(const base::android::JavaRef<jobject>& anchor,
                      const gfx::RectF& bounds);
 
+  gfx::Size GetPhysicalBackingSize();
+  void UpdateLayerBounds();
+
+  // Internal implementation of ViewClient forwarding calls to the interface.
+  void OnPhysicalBackingSizeChanged(int width, int height);
+
  protected:
   ViewAndroid* parent_;
 
  private:
   void RemoveChild(ViewAndroid* child);
 
+  // Checks if any ViewAndroid instance in the tree hierarchy (including
+  // all the parents and the children) has |EventHandler| already.
+  bool HasEventHandlerInTreeHierarchy();
+
+  // Checks if any children (plus this ViewAndroid itself) has |EventHandler|.
+  bool HasEventHandlerInSubtree();
+
   // Returns the Java delegate for this view. This is used to delegate work
   // up to the embedding view (or the embedder that can deal with the
   // implementation details).
   const base::android::ScopedJavaLocalRef<jobject>
       GetViewAndroidDelegate() const;
 
+  // Creates a new |EventHandler| for this ViewAndroid. No parent or child
+  // should have |EventHandler| for this ViewAndroid to have one.
+  virtual base::android::ScopedJavaLocalRef<jobject> CreateEventHandler(
+      ViewAndroid* native_view);
+
+  void SetPhysicalBackingSize(int width, int height) {

[boliu, 2016/12/08 05:01:06]

don't inline this

general rule is: inline is allowed for no-op, or simple getter only, ie the body
is a single line returning a member variable or a constant

[Jinsuk Kim, 2016/12/13 23:20:38]

You asked me to :/

217 void ViewAndroid::SetPhysicalBackingSize(int width, int height) {
boliu 2016/12/06 23:15:46
nit: maybe this can just be inlined, a bit confusing to have both this and
OnPhysicalBackingSizeChanged

[boliu, 2016/12/13 23:50:41]

Ohh... overloading the word "inline", I meant don't define this method at all,
and just move the body to where it's called, since there's only one call site.

[Jinsuk Kim, 2016/12/14 00:34:08]

I see. Should have made a better guess :) Done.

+    physical_width_pix_ = width;
+    physical_height_pix_ = height;
+    UpdateLayerBounds();
+  }
+
+  bool HasEventHandler() { return !event_handler_.is_uninitialized(); }

[boliu, 2016/12/08 05:01:06]

don't inline this

[Jinsuk Kim, 2016/12/13 23:20:38]

Done.

+
   std::list<ViewAndroid*> children_;
   scoped_refptr<cc::Layer> layer_;
   JavaObjectWeakGlobalRef delegate_;
+  JavaObjectWeakGlobalRef event_handler_;

[boliu, 2016/12/08 05:01:06]

this can actually be strong, we create EventHandler directly, and can ensure
it's not holding onto other objects strongly

[Jinsuk Kim, 2016/12/13 23:20:38]

Done. Now event handler is created directly in view_android.

+  ViewClient* const client_;
+
+  int physical_width_pix_;
+  int physical_height_pix_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);
 };