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..3d3aed81959aebd786b548b8284304b5d5d3a1f4 100644
--- a/ui/android/view_android.h
+++ b/ui/android/view_android.h
@@ -8,10 +8,13 @@
 #include <list>
 
 #include "base/android/jni_weak_ref.h"
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "ui/android/ui_android_export.h"
 #include "ui/gfx/geometry/rect_f.h"
 
+typedef unsigned int SkColor;
+
 namespace cc {
 class Layer;
 }
@@ -54,10 +57,6 @@ 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);
-
   ViewAndroid();
   virtual ~ViewAndroid();
 
@@ -84,6 +83,37 @@ class UI_ANDROID_EXPORT ViewAndroid {
   void SetAnchorRect(const base::android::JavaRef<jobject>& anchor,
                      const gfx::RectF& bounds);
 
+  void reset_physical_backing_size_changed_handler(
+      base::RepeatingCallback<void(int, int)> handler) {
+    // Handlers are stored in the view android that has the java delegate,
+    // which is unique in the implementation.
+    //
+    // This should be able to find the one to store the handler in before
+    // reaching the top view (or window, if not attached yet).
+    DCHECK(parent_);
+    if (delegate_.is_uninitialized())
+      parent_->reset_physical_backing_size_changed_handler(handler);
+    else
+      physical_backing_size_changed_handler_ = std::move(handler);
+  }
+
+  void reset_physical_backing_size_changed_handler() {
+    DCHECK(parent_);
+    if (delegate_.is_uninitialized())
+      parent_->reset_physical_backing_size_changed_handler();
+    else
+      physical_backing_size_changed_handler_.Reset();
+  }
+
+  void OnPhysicalBackingSizeChanged(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj,
+      jint width,
+      jint height);
+
+  // Register the ViewAndroid's native methods through JNI.
+  static bool RegisterViewAndroid(JNIEnv* env);
+
  protected:
   ViewAndroid* parent_;
 
@@ -100,6 +130,10 @@ class UI_ANDROID_EXPORT ViewAndroid {
   scoped_refptr<cc::Layer> layer_;
   JavaObjectWeakGlobalRef delegate_;
 
+  // Handler for calls coming down from Java layer.
+  base::RepeatingCallback<void(int, int)>
+      physical_backing_size_changed_handler_;
+
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);
 };