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 ce3e7c0cf2e1f0ef3d5daa5160a94ddc00085540..0e8a6ca285746283ef51cff0a0ec37a6d8ad3a2b 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -78,6 +78,8 @@
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/skia_util.h"
+#include "ui/keyboard/keyboard_controller.h"
+#include "ui/keyboard/keyboard_util.h"
 #include "ui/wm/public/activation_client.h"
 #include "ui/wm/public/scoped_tooltip_disabler.h"
 #include "ui/wm/public/tooltip_client.h"
@@ -1451,6 +1453,18 @@ void RenderWidgetHostViewAura::OnSwapCompositorFrame(
   }
 }
 
+float RenderWidgetHostViewAura::GetOverdrawBottomHeight() const {
+  float overdraw = 0.f;
+#if defined(OS_CHROMEOS)
+  gfx::Rect window_bounds = window_->GetBoundsInScreen();
+  gfx::Rect intersect = gfx::IntersectRects(window_bounds,
+                                            virtual_keyboard_bounds_);
+  if (intersect.height() > 0 && intersect.height() < window_bounds.height())
+    overdraw = intersect.height();
+#endif
+  return overdraw;
+}
+
 #if defined(OS_WIN)
 void RenderWidgetHostViewAura::SetParentNativeViewAccessible(
     gfx::NativeViewAccessible accessible_parent) {
@@ -3098,6 +3112,11 @@ void RenderWidgetHostViewAura::AddedToRootWindow() {
       input_method->SetFocusedTextInputClient(this);
   }
 
+  keyboard::KeyboardController* keyboard_controller =
+      keyboard::KeyboardController::GetInstance();
+  if (keyboard_controller)
+    keyboard_controller->AddObserver(this);
+
 #if defined(OS_WIN)
   // The parent may have changed here. Ensure that the legacy window is
   // reparented accordingly.
@@ -3122,6 +3141,11 @@ void RenderWidgetHostViewAura::RemovingFromRootWindow() {
 
   DetachFromInputMethod();
 
+  keyboard::KeyboardController* keyboard_controller =
+      keyboard::KeyboardController::GetInstance();
+  if (keyboard_controller)
+    keyboard_controller->RemoveObserver(this);
+
   window_->GetHost()->RemoveObserver(this);
   RunOnCommitCallbacks();
   resize_lock_.reset();
@@ -3212,6 +3236,22 @@ void RenderWidgetHostViewAura::OnLayerRecreated(ui::Layer* old_layer,
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// RenderWidgetHostViewAura, keyboard::KeyboardControllerObserver
+// implementation:
+
+void RenderWidgetHostViewAura::OnKeyboardBoundsChanging(
+    const gfx::Rect& new_bounds) {
+#if defined(OS_CHROMEOS)
+  if (!keyboard::IsKeyboardOverscrollEnabled())
+    return;
+  if (virtual_keyboard_bounds_ != new_bounds) {
+    virtual_keyboard_bounds_ = new_bounds;
+    host_->WasResized();
+  }
+#endif
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostView, public:
 
 // static