Makes browser resize content when root bounds change

mandoline/ui/browser/android/android_ui.cc

Index: mandoline/ui/browser/android/android_ui.cc
diff --git a/mandoline/ui/browser/android/android_ui.cc b/mandoline/ui/browser/android/android_ui.cc
index d9973669167adf094defeeb31b8fd7ff95f36b35..7cdbc72201e099e59427f6d3956a8b45528a0ff1 100644
--- a/mandoline/ui/browser/android/android_ui.cc
+++ b/mandoline/ui/browser/android/android_ui.cc
@@ -5,6 +5,8 @@
 #include "mandoline/ui/browser/android/android_ui.h"
 
 #include "components/view_manager/public/cpp/view.h"
+#include "mojo/converters/geometry/geometry_type_converters.h"
+#include "ui/gfx/geometry/rect.h"
 
 namespace mandoline {
 
@@ -13,15 +15,26 @@ AndroidUI::AndroidUI(Browser* browser, mojo::Shell* shell)
       shell_(shell),
       root_(nullptr),
       content_(nullptr) {}
-AndroidUI::~AndroidUI() {}
+
+AndroidUI::~AndroidUI() {
+  root_->RemoveObserver(this);
+}
 
 void AndroidUI::Init(mojo::View* root, mojo::View* content) {
   root_ = root;
+  root_->AddObserver(this);
   content_ = content;
 
   content_->SetBounds(root_->bounds());
 }
 
+void AndroidUI::OnViewBoundsChanged(mojo::View* view,
+                                    const mojo::Rect& old_bounds,
+                                    const mojo::Rect& new_bounds) {
+  content_->SetBounds(
+      *mojo::Rect::From(gfx::Rect(0, 0, new_bounds.width, new_bounds.height)));
+}
+
 // static
 BrowserUI* BrowserUI::Create(Browser* browser, mojo::Shell* shell) {
   return new AndroidUI(browser, shell);