Honor overscroll-behavior CSS property in new gesture-nav UI

When overscroll-behavior-x for the root element of a page is set to
anything other than 'auto', gesture-nav should not start on the page.

Similarly, when overscroll-behavior-y for the root element of a page is
set to anything other than 'auto', pull-to-refresh should not start on
the page.

BUG=800074,742510
TEST=GestureNavSimpleTest.* in content_unittests

Change-Id: I86cf2f50c5ceb6613dc293c1fd32ca2cfff4daa2
Reviewed-on: https://chromium-review.googlesource.com/981127Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Mohsen Izadi <mohsen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546736}

content/browser/web_contents/aura/gesture_nav_simple.cc

@@ -555,6 +555,12 @@ bool GestureNavSimple::OnOverscrollUpdate(float delta_x, float delta_y) {
 }
 
 void GestureNavSimple::OnOverscrollComplete(OverscrollMode overscroll_mode) {
+  if (mode_ == OverscrollMode::OVERSCROLL_NONE) {
+    // Previous mode change has been ignored because of overscroll-behavior
+    // value; so, ignore this, too.
+    return;
+  }
+
   DCHECK_EQ(mode_, overscroll_mode);
 
   mode_ = OVERSCROLL_NONE;
@@ -599,6 +605,29 @@ void GestureNavSimple::OnOverscrollModeChange(OverscrollMode old_mode,
                                               OverscrollMode new_mode,
                                               OverscrollSource source,
                                               cc::OverscrollBehavior behavior) {
+  DCHECK(old_mode == OverscrollMode::OVERSCROLL_NONE ||
+         new_mode == OverscrollMode::OVERSCROLL_NONE);
+
+  // Do not start a new gesture-nav if overscroll-behavior-x is not auto.
+  if ((new_mode == OverscrollMode::OVERSCROLL_EAST ||
+       new_mode == OverscrollMode::OVERSCROLL_WEST) &&
+      behavior.x != cc::OverscrollBehavior::kOverscrollBehaviorTypeAuto) {
+    return;
+  }
+
+  // Do not start a new pull-to-refresh if overscroll-behavior-y is not auto.
+  if (new_mode == OverscrollMode::OVERSCROLL_SOUTH &&
+      behavior.y != cc::OverscrollBehavior::kOverscrollBehaviorTypeAuto) {
+    return;
+  }
+
+  if (old_mode != OverscrollMode::OVERSCROLL_NONE &&
+      mode_ == OverscrollMode::OVERSCROLL_NONE) {
+    // Previous mode change has been ignored because of overscroll-behavior
+    // value; so, ignore this one, too.
+    return;
+  }
+
   DCHECK_EQ(mode_, old_mode);
   if (mode_ == new_mode)
     return;

content/browser/web_contents/aura/gesture_nav_simple.h

@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/common/content_export.h"
 
 namespace content {
 
@@ -17,7 +18,7 @@ class WebContentsImpl;
 
 // A simple delegate for the overscroll controller that paints an arrow on top
 // of the web-contents as a hint for pending navigations from overscroll.
-class GestureNavSimple : public OverscrollControllerDelegate {
+class CONTENT_EXPORT GestureNavSimple : public OverscrollControllerDelegate {
  public:
   explicit GestureNavSimple(WebContentsImpl* web_contents);
   ~GestureNavSimple() override;
@@ -27,6 +28,8 @@ class GestureNavSimple : public OverscrollControllerDelegate {
   void OnAffordanceAnimationEnded();
 
  private:
+  friend class GestureNavSimpleTest;
+
   // OverscrollControllerDelegate:
   gfx::Size GetDisplaySize() const override;
   bool OnOverscrollUpdate(float delta_x, float delta_y) override;

content/test/BUILD.gn

@@ -1497,6 +1497,7 @@ test("content_unittests") {
     "../browser/tracing/background_memory_tracing_observer_unittest.cc",
     "../browser/tracing/background_tracing_config_unittest.cc",
     "../browser/tracing/tracing_ui_unittest.cc",
+    "../browser/web_contents/aura/gesture_nav_simple_unittest.cc",
     "../browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc",
     "../browser/web_contents/aura/overscroll_window_animation_unittest.cc",
     "../browser/web_contents/aura/overscroll_window_delegate_unittest.cc",
@@ -2025,6 +2026,7 @@ test("content_unittests") {
   } else {
     sources -= [
       "../browser/renderer_host/render_widget_host_view_aura_unittest.cc",
+      "../browser/web_contents/aura/gesture_nav_simple_unittest.cc",
       "../browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc",
       "../browser/web_contents/aura/overscroll_window_animation_unittest.cc",
       "../browser/web_contents/aura/overscroll_window_delegate_unittest.cc",