Implement overscroll support for the virtual keyboard.

content/public/browser/render_widget_host_view.h

Index: content/public/browser/render_widget_host_view.h
diff --git a/content/public/browser/render_widget_host_view.h b/content/public/browser/render_widget_host_view.h
index 821dc21bf657328bb5ea8ec10829a353ab48745d..24f66035c2df8d337db5b07fe0a9f83fe2bf1863 100644
--- a/content/public/browser/render_widget_host_view.h
+++ b/content/public/browser/render_widget_host_view.h
@@ -114,6 +114,15 @@ class CONTENT_EXPORT RenderWidgetHostView {
   // Returns true if the mouse pointer is currently locked.
   virtual bool IsMouseLocked() = 0;
 
+  // Retrives the size of the viewport for the visible region. May be smaller
+  // than the view size if a portion of the view is obstructed (e.g. by a
+  // virtual keyboard).
+  virtual gfx::SizeF GetVisibleViewportSize() const = 0;

[sky, 2014/04/24 15:55:09]

Why is this floating point when nothing else in this class is?

[kevers, 2014/04/24 18:38:33]

Based on suggestion by aelias.  Android makes significant use of floating point
scale factors (e.g. overdraw_bottom_height).  Currently, we have rounding on
both the browser side and Blink. The suggestion to use float is based on the
direction Android seems to be moving. Switching  to integer for now as it can
always be changed to float later as needed.

+
+  // Set insets for the visible region of the root window. Used to compute the
+  // visible viewport.
+  virtual void SetInsets(const gfx::Insets& insets) = 0;
+
 #if defined(OS_MACOSX)
   // Set the view's active state (i.e., tint state of controls).
   virtual void SetActive(bool active) = 0;