Revert BrowserControlsOffsetManager changes

cc/input/browser_controls_offset_manager.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/input/browser_controls_offset_manager.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 
@@ skipping 42 matching lines @@
 BrowserControlsOffsetManager::~BrowserControlsOffsetManager() {}
 
 float BrowserControlsOffsetManager::ControlsTopOffset() const {
   return ContentTopOffset() - TopControlsHeight();
 }
 
 float BrowserControlsOffsetManager::ContentTopOffset() const {
   return TopControlsShownRatio() * TopControlsHeight();
 }
 
-float BrowserControlsOffsetManager::ContentOffsetInternal() const {
-  if (!TopControlsHeight())
-    return BottomControlsShownRatio() * BottomControlsHeight();
-  return ContentTopOffset();
-}
-
 float BrowserControlsOffsetManager::TopControlsShownRatio() const {
   return client_->CurrentBrowserControlsShownRatio();
 }
 
 float BrowserControlsOffsetManager::TopControlsHeight() const {
   return client_->TopControlsHeight();
 }
 
 float BrowserControlsOffsetManager::BottomControlsHeight() const {
   return client_->BottomControlsHeight();
@@ skipping 40 matching lines @@
 void BrowserControlsOffsetManager::ScrollBegin() {
   if (pinch_gesture_active_)
     return;
 
   ResetAnimations();
   ResetBaseline();
 }
 
 gfx::Vector2dF BrowserControlsOffsetManager::ScrollBy(
     const gfx::Vector2dF& pending_delta) {
-  // If one or both of the top/bottom controls are showing, the shown ratio
-  // needs to be computed.
-  float controls_height =
-      TopControlsHeight() ? TopControlsHeight() : BottomControlsHeight();
-
-  if (!controls_height)
+  if (!TopControlsHeight())
     return pending_delta;
 
   if (pinch_gesture_active_)
     return pending_delta;
 
   if (permitted_state_ == SHOWN && pending_delta.y() > 0)
     return pending_delta;
   else if (permitted_state_ == HIDDEN && pending_delta.y() < 0)
     return pending_delta;
 
   accumulated_scroll_delta_ += pending_delta.y();
 
-  float old_offset = ContentOffsetInternal();
+  float old_offset = ContentTopOffset();
   client_->SetCurrentBrowserControlsShownRatio(
-      (baseline_content_offset_ - accumulated_scroll_delta_) / controls_height);
+      (baseline_content_offset_ - accumulated_scroll_delta_) /
+      TopControlsHeight());
 
   // If the controls are fully visible, treat the current position as the
   // new baseline even if the gesture didn't end.
   if (TopControlsShownRatio() == 1.f)
     ResetBaseline();
 
   ResetAnimations();
 
-  gfx::Vector2dF applied_delta(0.f, old_offset - ContentOffsetInternal());
+  gfx::Vector2dF applied_delta(0.f, old_offset - ContentTopOffset());
   return pending_delta - applied_delta;
 }
 
 void BrowserControlsOffsetManager::ScrollEnd() {
   if (pinch_gesture_active_)
     return;
 
   StartAnimationIfNecessary();
 }
 
@@ skipping 13 matching lines @@
 
 void BrowserControlsOffsetManager::MainThreadHasStoppedFlinging() {
   StartAnimationIfNecessary();
 }
 
 gfx::Vector2dF BrowserControlsOffsetManager::Animate(
     base::TimeTicks monotonic_time) {
   if (!has_animation() || !client_->HaveRootScrollLayer())
     return gfx::Vector2dF();
 
-  float old_offset = ContentOffsetInternal();
+  float old_offset = ContentTopOffset();
   float new_ratio = gfx::Tween::ClampedFloatValueBetween(
       monotonic_time, animation_start_time_, animation_start_value_,
       animation_stop_time_, animation_stop_value_);
   client_->SetCurrentBrowserControlsShownRatio(new_ratio);
 
   if (IsAnimationComplete(new_ratio))
     ResetAnimations();
 
-  gfx::Vector2dF scroll_delta(0.f, ContentOffsetInternal() - old_offset);
+  gfx::Vector2dF scroll_delta(0.f, ContentTopOffset() - old_offset);
   return scroll_delta;
 }
 
 void BrowserControlsOffsetManager::ResetAnimations() {
   animation_start_time_ = base::TimeTicks();
   animation_start_value_ = 0.f;
   animation_stop_time_ = base::TimeTicks();
   animation_stop_value_ = 0.f;
 
   animation_direction_ = NO_ANIMATION;
 }
 
 void BrowserControlsOffsetManager::SetupAnimation(
     AnimationDirection direction) {
   DCHECK_NE(NO_ANIMATION, direction);
   DCHECK(direction != HIDING_CONTROLS || TopControlsShownRatio() > 0.f);
   DCHECK(direction != SHOWING_CONTROLS || TopControlsShownRatio() < 1.f);
 
   if (has_animation() && animation_direction_ == direction)
     return;
 
-  if (!TopControlsHeight() && !BottomControlsHeight()) {
+  if (!TopControlsHeight()) {
     client_->SetCurrentBrowserControlsShownRatio(
         direction == HIDING_CONTROLS ? 0.f : 1.f);
     return;
   }
 
   animation_start_time_ = base::TimeTicks::Now();
   animation_start_value_ = TopControlsShownRatio();
 
   const float max_ending_ratio = (direction == SHOWING_CONTROLS ? 1 : -1);
   animation_stop_time_ =
@@ skipping 24 matching lines @@
   }
 }
 
 bool BrowserControlsOffsetManager::IsAnimationComplete(float new_ratio) {
   return (animation_direction_ == SHOWING_CONTROLS && new_ratio >= 1.f) ||
          (animation_direction_ == HIDING_CONTROLS && new_ratio <= 0.f);
 }
 
 void BrowserControlsOffsetManager::ResetBaseline() {
   accumulated_scroll_delta_ = 0.f;
-  baseline_content_offset_ = ContentOffsetInternal();
+  baseline_content_offset_ = ContentTopOffset();
 }
 
 }  // namespace cc