Implement initial version of scroll end effect

chrome/browser/ui/views/frame/contents_container.cc

Index: chrome/browser/ui/views/frame/contents_container.cc
diff --git a/chrome/browser/ui/views/frame/contents_container.cc b/chrome/browser/ui/views/frame/contents_container.cc
index 9461aa99b2408bca73bd0eaadc0c5119e72f5f61..8f3a7e299ec71a9a7ceaf904aaf18bdd4b8544f2 100644
--- a/chrome/browser/ui/views/frame/contents_container.cc
+++ b/chrome/browser/ui/views/frame/contents_container.cc
@@ -4,9 +4,15 @@
 
 #include "chrome/browser/ui/views/frame/contents_container.h"
 
-ContentsContainer::ContentsContainer(views::View* active_web_view)
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_view.h"
+#include "ui/aura/window.h"
+#include "ui/views/controls/webview/webview.h"
+
+ContentsContainer::ContentsContainer(views::WebView* active_web_view)
     : active_web_view_(active_web_view),
-      active_top_margin_(0) {
+      active_top_margin_(0),
+      scroll_effect_active_(false) {
   AddChildView(active_web_view_);
 }
 
@@ -24,11 +30,44 @@ bool ContentsContainer::SetActiveTopMargin(int margin) {
   return true;
 }
 
+void ContentsContainer::ActivateScrollEndEffect() {
+  scroll_effect_active_ = true;
+  active_web_view_->SetFastResize(true);
+  web_view_bounds_ = active_web_view_->bounds();
+  Layout();
+}
+
+void ContentsContainer::DeactivateScrollEndEffect() {
+  if (scroll_effect_active_ == false)
+    return;
+  scroll_effect_active_ = false;
+  active_web_view_->SetFastResize(false);
+  active_web_view_->SetBoundsRect(web_view_bounds_);
+  Layout();
+}
+
+void ContentsContainer::UpdateScrollEndEffectHeightDelta(int height_delta,
+                                                         bool scrolling_down) {
+  DCHECK(scroll_effect_active_);
+
+  gfx::Rect clipping_bounds = web_view_bounds_;
+  clipping_bounds.set_height(clipping_bounds.height() - height_delta);
+  if (scrolling_down) {
+    active_web_view_->SetFastResizeGravity(
+        views::NativeViewHost::GRAVITY_NORTH);
+  } else {
+    active_web_view_->SetFastResizeGravity(
+        views::NativeViewHost::GRAVITY_SOUTH);
+  }
+  active_web_view_->SetBoundsRect(clipping_bounds);
+}
+
 void ContentsContainer::Layout() {
   int content_y = active_top_margin_;
   int content_height = std::max(0, height() - content_y);
 
-  active_web_view_->SetBounds(0, content_y, width(), content_height);
+  if (!scroll_effect_active_)
+    active_web_view_->SetBounds(0, content_y, width(), content_height);
 
   // Need to invoke views::View in case any views whose bounds didn't change
   // still need a layout.