Introduce ViewRoot forwarding input/view events to native

ui/android/view_android.cc

Index: ui/android/view_android.cc
diff --git a/ui/android/view_android.cc b/ui/android/view_android.cc
index 96e56495886dd26d8807a5847a0d6f0e12894295..db41fa143d9ac34aab9d764130cc4713f53426e6 100644
--- a/ui/android/view_android.cc
+++ b/ui/android/view_android.cc
@@ -9,7 +9,6 @@
 #include "base/android/jni_android.h"
 #include "cc/layers/layer.h"
 #include "jni/ViewAndroidDelegate_jni.h"
-#include "jni/ViewRoot_jni.h"
 #include "ui/android/view_client.h"
 #include "ui/android/window_android.h"
 #include "ui/display/display.h"
@@ -84,11 +83,6 @@ ViewAndroid::~ViewAndroid() {
     DCHECK_EQ(child->parent_, this);
     child->parent_ = nullptr;
   }
-
-  JNIEnv* env = base::android::AttachCurrentThread();
-  const ScopedJavaLocalRef<jobject> view_root = view_root_.get(env);
-  if (!view_root.is_null())
-    Java_ViewRoot_onDestroyNativeView(env, view_root);
 }
 
 void ViewAndroid::SetDelegate(const JavaRef<jobject>& delegate) {
@@ -100,18 +94,17 @@ void ViewAndroid::SetDelegate(const JavaRef<jobject>& delegate) {
 
 void ViewAndroid::AddChild(ViewAndroid* child) {
   DCHECK(child);
+  DCHECK(!child->IsViewRoot());  // ViewRoot cannot be a child.
   DCHECK(std::find(children_.begin(), children_.end(), child) ==
          children_.end());
-  DCHECK(!HasViewRootInTreeHierarchy() ||
-         !child->HasViewRootInSubtree());
 
   children_.push_back(child);
   if (child->parent_)
     child->RemoveFromParent();
   child->parent_ = this;
   if (physical_width_pix_ || physical_height_pix_) {
-    child->OnPhysicalBackingSizeChanged(physical_width_pix_,
-                                        physical_height_pix_);
+    child->OnPhysicalBackingSizeChangedInternal(physical_width_pix_,
+                                                physical_height_pix_);
   }
 }
 
@@ -165,15 +158,6 @@ WindowAndroid* ViewAndroid::GetWindowAndroid() const {
   return parent_ ? parent_->GetWindowAndroid() : nullptr;
 }
 
-ScopedJavaLocalRef<jobject> ViewAndroid::CreateViewRoot() {
-  JNIEnv* env = base::android::AttachCurrentThread();
-  return Java_ViewRoot_create(env, reinterpret_cast<intptr_t>(this));
-}
-
-bool ViewAndroid::HasViewRoot() {
-  return !view_root_.is_uninitialized();
-}
-
 const ScopedJavaLocalRef<jobject> ViewAndroid::GetViewAndroidDelegate()
     const {
   JNIEnv* env = base::android::AttachCurrentThread();
@@ -193,35 +177,12 @@ void ViewAndroid::SetLayer(scoped_refptr<cc::Layer> layer) {
   UpdateLayerBounds();
 }
 
-ScopedJavaLocalRef<jobject> ViewAndroid::GetViewRoot() {
-  JNIEnv* env = base::android::AttachCurrentThread();
-  const ScopedJavaLocalRef<jobject> view_root = view_root_.get(env);
-  if (!view_root.is_null())
-     return view_root;
-
-  DCHECK(!HasViewRootInTreeHierarchy());
-  view_root_ = JavaObjectWeakGlobalRef(env, CreateViewRoot());
-  return view_root_.get(env);
-}
-
-bool ViewAndroid::HasViewRootInTreeHierarchy() {
-  ViewAndroid* view = parent_;
-  while (view) {
-    if (view->HasViewRoot())
-      return true;
-    view = view->parent_;
-  }
-  return HasViewRootInSubtree();
+ViewAndroid* ViewAndroid::GetViewRoot() {
+  return parent_ ? parent_->GetViewRoot() : nullptr;
 }
 
-bool ViewAndroid::HasViewRootInSubtree() {
-  if (HasViewRoot())
-    return true;
-  for (auto& child : children_) {
-    if (child->HasViewRootInSubtree())
-      return true;
-  }
-  return false;
+bool ViewAndroid::IsViewRoot() {
+  return GetViewRoot() == this;
 }
 
 bool ViewAndroid::StartDragAndDrop(const JavaRef<jstring>& jtext,
@@ -243,7 +204,7 @@ void ViewAndroid::UpdateLayerBounds() {
     layer_->SetBounds(GetPhysicalBackingSize());
 }
 
-void ViewAndroid::OnPhysicalBackingSizeChanged(int width, int height) {
+void ViewAndroid::OnPhysicalBackingSizeChangedInternal(int width, int height) {
   if (width == physical_width_pix_ && height == physical_height_pix_)
     return;
 
@@ -255,21 +216,7 @@ void ViewAndroid::OnPhysicalBackingSizeChanged(int width, int height) {
     client_->OnPhysicalBackingSizeChanged(width, height);
 
   for (auto& child : children_)
-    child->OnPhysicalBackingSizeChanged(width, height);
-}
-
-// static
-void OnPhysicalBackingSizeChanged(JNIEnv* env,
-                                  const JavaParamRef<jclass>& jcaller,
-                                  jlong native_view,
-                                  int width,
-                                  int height) {
-  ViewAndroid* view_android = reinterpret_cast<ViewAndroid*>(native_view);
-  view_android->OnPhysicalBackingSizeChanged(width, height);
-}
-
-bool RegisterViewRoot(JNIEnv* env) {
-  return RegisterNativesImpl(env);
+    child->OnPhysicalBackingSizeChangedInternal(width, height);
 }
 
 }  // namespace ui