Implement overscroll support for the virtual keyboard.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index ad374246f96ac5d750fb9703868bb584f8262ff5..2ff8ac8086548fb81fd1dea5ac6aca5ee52970f9 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -875,6 +875,23 @@ void RenderWidgetHostViewAura::SetBackground(const SkBitmap& background) {
   window_->layer()->SetFillsBoundsOpaquely(background.isOpaque());
 }
 
+int RenderWidgetHostViewAura::GetVisibleViewportHeight() const {
+  gfx::Rect window_bounds = window_->GetBoundsInScreen();
+  gfx::Rect intersect = gfx::IntersectRects(window_bounds,
+                                            virtual_keyboard_bounds_);
+  int overlap = intersect.height();
+  if (overlap > 0 && overlap < window_bounds.height())
+    return window_bounds.height() - overlap;
+  return GetViewBounds().height();
+}
+
+void RenderWidgetHostViewAura::SetKeyboardBounds(const gfx::Rect& bounds) {

[sky, 2014/04/23 20:47:08]

Is there a reason you can't set an insets? I'm thinking of an API like:

SetInsets(const gfx::Insets& insets);

I also don't like that the coordinates of this function are screen. That makes
it super easy to get wrong.

[kevers, 2014/04/23 20:57:49]

The reason for explicitly using screen coordinates is that the keyboard is only
displayed on the primary root window.  SetInsets would work well if the clipping
applied across all displays.

[sky, 2014/04/23 21:15:31]

Isn't that an implementation detail? Can't the keyboard figure out the insets
and set it?

[kevers, 2014/04/24 02:02:13]

Done.

+  if (bounds != virtual_keyboard_bounds_) {
+    virtual_keyboard_bounds_ = bounds;
+    host_->WasResized();
+  }
+}
+
 void RenderWidgetHostViewAura::UpdateCursor(const WebCursor& cursor) {
   current_cursor_ = cursor;
   const gfx::Display display = gfx::Screen::GetScreenFor(window_)->