Upstream FullscreenManager

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java b/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..974ff2037ff4793325de81dfde61a45289f14e5c
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
@@ -0,0 +1,721 @@
+// Copyright 2014 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.
+
+package org.chromium.chrome.browser.fullscreen;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
+import android.app.Activity;
+import android.content.res.Resources;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Message;
+import android.os.SystemClock;
+import android.util.Property;
+import android.view.Gravity;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.ViewGroup.LayoutParams;
+import android.view.Window;
+import android.widget.FrameLayout;
+
+import org.chromium.base.ActivityState;
+import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.base.ApplicationStatus;
+import org.chromium.base.ApplicationStatus.ActivityStateListener;
+import org.chromium.base.BaseChromiumApplication;
+import org.chromium.base.BaseChromiumApplication.WindowFocusChangedListener;
+import org.chromium.base.TraceEvent;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.chrome.browser.Tab;
+import org.chromium.chrome.browser.fullscreen.FullscreenHtmlApiHandler.FullscreenHtmlApiDelegate;
+import org.chromium.chrome.browser.tabmodel.TabModelSelector;
+import org.chromium.content.browser.ContentViewCore;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+
+/**
+ * A class that manages control and content views to create the fullscreen mode.
+ */
+public class ChromeFullscreenManager
+        extends FullscreenManager implements ActivityStateListener, WindowFocusChangedListener {
+    // Minimum showtime of the toolbar (in ms).
+    private static final long MINIMUM_SHOW_DURATION_MS = 3000;
+
+    // Maximum length of the slide in/out animation of the toolbar (in ms).
+    private static final long MAX_ANIMATION_DURATION_MS = 500;
+
+    private static final int MSG_ID_CONTROLS_REQUEST_LAYOUT = 1;
+    private static final int MSG_ID_HIDE_CONTROLS = 2;
+
+    private final HashSet<Integer> mPersistentControlTokens = new HashSet<Integer>();
+
+    private final Activity mActivity;
+    private final Window mWindow;
+    private final Handler mHandler;
+    private final int mControlContainerHeight;
+
+    private View mControlContainer;
+
+    private long mMinShowNotificationMs = MINIMUM_SHOW_DURATION_MS;
+    private long mMaxAnimationDurationMs = MAX_ANIMATION_DURATION_MS;
+
+    private final boolean mEnabled;
+
+    private float mBrowserControlOffset = Float.NaN;
+    private float mRendererControlOffset = Float.NaN;
+    private float mRendererContentOffset;
+    private float mPreviousContentOffset;
+    private float mControlOffset;
+    private float mPreviousControlOffset;
+    private boolean mIsEnteringPersistentModeState;
+
+    private boolean mInGesture;
+    private boolean mContentViewScrolling;
+
+    private int mPersistentControlsCurrentToken;
+    private long mCurrentShowTime;
+
+    private ObjectAnimator mControlAnimation;
+    private boolean mCurrentAnimationIsShowing;
+
+    private boolean mDisableBrowserOverride;
+
+    private boolean mTopControlsPermanentlyHidden;
+    private boolean mTopControlsAndroidViewHidden;
+
+    private final ArrayList<FullscreenListener> mListeners = new ArrayList<FullscreenListener>();
+
+    /**
+     * A listener that gets notified of changes to the fullscreen state.
+     */
+    public interface FullscreenListener {
+        /**
+         * Called whenever the content's offset changes.
+         * @param offset The new offset of the content from the top of the screen.
+         */
+        public void onContentOffsetChanged(float offset);
+
+        /**
+         * Called whenever the content's visible offset changes.
+         * @param offset The new offset of the visible content from the top of the screen.
+         */
+        public void onVisibleContentOffsetChanged(float offset);
+
+        /**
+         * Called when a ContentVideoView is created/destroyed.
+         * @param enabled Whether to enter or leave overlay video mode.
+         */
+        public void onToggleOverlayVideoMode(boolean enabled);
+    }
+
+    private class ControlsOffsetProperty extends Property<ChromeFullscreenManager, Float> {
+        public ControlsOffsetProperty() {
+            super(Float.class, "controlsOffset");
+        }
+
+        @Override
+        public Float get(ChromeFullscreenManager object) {
+            return getControlOffset();
+        }
+
+        @Override
+        public void set(ChromeFullscreenManager manager, Float offset) {
+            if (mDisableBrowserOverride) return;
+            float browserOffset = offset.floatValue();
+            if (Float.compare(mBrowserControlOffset, browserOffset) == 0) return;
+            mBrowserControlOffset = browserOffset;
+            manager.updateControlOffset();
+            manager.updateVisuals();
+        }
+    }
+
+    private final Runnable mUpdateVisibilityRunnable = new Runnable() {
+        @Override
+        public void run() {
+            int visibility = shouldShowAndroidControls() ? View.VISIBLE : View.INVISIBLE;
+            if (mControlContainer.getVisibility() == visibility) return;
+            // requestLayout is required to trigger a new gatherTransparentRegion(), which
+            // only occurs together with a layout and let's SurfaceFlinger trim overlays.
+            // This may be almost equivalent to using View.GONE, but we still use View.INVISIBLE
+            // since drawing caches etc. won't be destroyed, and the layout may be less expensive.
+            mControlContainer.setVisibility(visibility);
+            mControlContainer.requestLayout();
+        }
+    };
+
+    /**
+     * Creates an instance of the fullscreen mode manager.
+     * @param activity The activity that supports fullscreen.
+     * @param controlContainer Container holding the controls (Toolbar).
+     * @param enabled Whether fullscreen is globally enabled.
+     * @param modelSelector The model selector providing access to the current tab.
+     */
+    public ChromeFullscreenManager(Activity activity, View controlContainer, boolean enabled,
+            boolean persistentFullscreenSupported, TabModelSelector modelSelector,
+            int resControlContainerHeight) {
+        super(activity.getWindow(), modelSelector, enabled, persistentFullscreenSupported);
+
+        mActivity = activity;
+        ApplicationStatus.registerStateListenerForActivity(this, activity);
+        ((BaseChromiumApplication) activity.getApplication())
+                .registerWindowFocusChangedListener(this);
+
+        mWindow = activity.getWindow();
+        mHandler = new Handler() {
+            @Override
+            public void handleMessage(Message msg) {
+                if (msg == null) return;
+                switch (msg.what) {
+                    case MSG_ID_CONTROLS_REQUEST_LAYOUT:
+                        mControlContainer.requestLayout();
+                        break;
+                    case MSG_ID_HIDE_CONTROLS:
+                        update(false);
+                        break;
+                    default:
+                        assert false : "Unexpected message for ID: " + msg.what;
+                        break;
+                }
+            }
+        };
+        setControlContainer(controlContainer);
+        Resources resources = mWindow.getContext().getResources();
+        mControlContainerHeight = resources.getDimensionPixelSize(resControlContainerHeight);
+        mRendererContentOffset = mControlContainerHeight;
+        mEnabled = enabled;
+        updateControlOffset();
+    }
+
+    /**
+     * @return Whether or not fullscreen is enabled.
+     */
+    public boolean isEnabled() {
+        return mEnabled;
+    }
+
+    /**
+     * Set the control container that is being hidden and shown when manipulating the fullscreen
+     * state.
+     * @param controlContainer The container at the top of the screen that contains the controls.
+     */
+    public void setControlContainer(View controlContainer) {
+        assert controlContainer != null;
+        mControlContainer = controlContainer;
+    }
+
+    @Override
+    public void onActivityStateChange(Activity activity, int newState) {
+        if (newState == ActivityState.STOPPED) {
+            // Exit fullscreen in onStop to ensure the system UI flags are set correctly when
+            // showing again (on JB MR2+ builds, the omnibox would be covered by the
+            // notification bar when this was done in onStart()).
+            setPersistentFullscreenMode(false);
+        } else if (newState == ActivityState.STARTED) {
+            showControlsTransient();
+        } else if (newState == ActivityState.DESTROYED) {
+            ApplicationStatus.unregisterActivityStateListener(this);
+            ((BaseChromiumApplication) mWindow.getContext().getApplicationContext())
+                    .unregisterWindowFocusChangedListener(this);
+        }
+    }
+
+    @Override
+    public void onWindowFocusChanged(Activity activity, boolean hasFocus) {
+        if (mActivity == activity) onWindowFocusChanged(hasFocus);
+    }
+
+    @Override
+    protected FullscreenHtmlApiDelegate createApiDelegate() {
+        return new FullscreenHtmlApiDelegate() {
+            @Override
+            public View getNotificationAnchorView() {
+                return mControlContainer;
+            }
+
+            @Override
+            public int getNotificationOffsetY() {
+                return (int) getControlOffset();
+            }
+
+            @Override
+            public void onEnterFullscreen() {
+                mIsEnteringPersistentModeState = true;
+            }
+
+            @Override
+            public boolean cancelPendingEnterFullscreen() {
+                boolean wasPending = mIsEnteringPersistentModeState;
+                mIsEnteringPersistentModeState = false;
+                return wasPending;
+            }
+
+            @Override
+            public void onFullscreenExited(ContentViewCore contentViewCore) {
+                contentViewCore.getWebContents().updateTopControlsState(false, true, true);
+                contentViewCore.getWebContents().updateTopControlsState(true, true, false);
+            }
+
+            @Override
+            public boolean shouldShowNotificationBubble() {
+                return !isOverlayVideoMode();
+            }
+        };
+    }
+
+    /**
+     * Disables the ability for the browser to override the renderer provided top controls
+     * position for testing.
+     */
+    @VisibleForTesting
+    public void disableBrowserOverrideForTest() {
+        mDisableBrowserOverride = true;
+        mPersistentControlTokens.clear();
+        mHandler.removeMessages(MSG_ID_HIDE_CONTROLS);
+        if (mControlAnimation != null) {
+            mControlAnimation.cancel();
+            mControlAnimation = null;
+        }
+        mBrowserControlOffset = Float.NaN;
+        updateVisuals();
+    }
+
+    /**
+     * Allows tests to override the animation durations for faster tests.
+     * @param minShowDuration The minimum time the controls must be shown.
+     * @param maxAnimationDuration The maximum animation time to show/hide the controls.
+     */
+    @VisibleForTesting
+    public void setAnimationDurationsForTest(long minShowDuration, long maxAnimationDuration) {
+        mMinShowNotificationMs = minShowDuration;
+        mMaxAnimationDurationMs = maxAnimationDuration;
+    }
+
+    @Override
+    public void showControlsTransient() {
+        if (mPersistentControlTokens.isEmpty()) update(true);
+    }
+
+    @Override
+    public int showControlsPersistent() {
+        int token = mPersistentControlsCurrentToken++;
+        mPersistentControlTokens.add(token);
+        if (mPersistentControlTokens.size() == 1) update(true);
+        return token;
+    }
+
+    @Override
+    public int showControlsPersistentAndClearOldToken(int oldToken) {
+        if (oldToken != INVALID_TOKEN) mPersistentControlTokens.remove(oldToken);
+        return showControlsPersistent();
+    }
+
+    @Override
+    public void hideControlsPersistent(int token) {
+        if (mPersistentControlTokens.remove(token) && mPersistentControlTokens.isEmpty()) {
+            update(false);
+        }
+    }
+
+    /**
+     * @param remove Whether or not to forcefully remove the toolbar.
+     */
+    public void setTopControlsPermamentlyHidden(boolean remove) {
+        if (remove == mTopControlsPermanentlyHidden) return;
+        mTopControlsPermanentlyHidden = remove;
+        updateVisuals();
+    }
+
+    /**
+     * @return Whether or not the toolbar is forcefully being removed.
+     */
+    public boolean areTopControlsPermanentlyHidden() {
+        return mTopControlsPermanentlyHidden;
+    }
+
+    /**
+     * @return Whether the top controls should be drawn as a texture.
+     */
+    public boolean drawControlsAsTexture() {
+        return getControlOffset() > -mControlContainerHeight;
+    }
+
+    /**
+     * @return The height of the top controls in pixels.
+     */
+    public int getTopControlsHeight() {
+        return mEnabled ? mControlContainerHeight : 0;
+    }
+
+    @Override
+    public float getContentOffset() {
+        if (!mEnabled || mTopControlsPermanentlyHidden) return 0;
+        return rendererContentOffset();
+    }
+
+    /**
+     * @return The offset of the controls from the top of the screen.
+     */
+    public float getControlOffset() {
+        if (!mEnabled) return 0;
+        if (mTopControlsPermanentlyHidden) return -getTopControlsHeight();
+        return mControlOffset;
+    }
+
+    @SuppressWarnings("SelfEquality")
+    private void updateControlOffset() {
+        float offset = 0;
+        // Inline Float.isNan with "x != x":
+        final boolean isNaNBrowserControlOffset = mBrowserControlOffset != mBrowserControlOffset;
+        final float rendererControlOffset = rendererControlOffset();
+        final boolean isNaNRendererControlOffset = rendererControlOffset != rendererControlOffset;
+        if (!isNaNBrowserControlOffset || !isNaNRendererControlOffset) {
+            offset = Math.max(
+                    isNaNBrowserControlOffset ? -mControlContainerHeight : mBrowserControlOffset,
+                    isNaNRendererControlOffset ? -mControlContainerHeight : rendererControlOffset);
+        }
+        mControlOffset = offset;
+    }
+
+    @Override
+    public void setOverlayVideoMode(boolean enabled) {
+        super.setOverlayVideoMode(enabled);
+
+        for (int i = 0; i < mListeners.size(); i++) {
+            mListeners.get(i).onToggleOverlayVideoMode(enabled);
+        }
+    }
+
+    /**
+     * @return Whether the browser has a control offset override.
+     */
+    @VisibleForTesting
+    public boolean hasBrowserControlOffsetOverride() {
+        return !Float.isNaN(mBrowserControlOffset) || mControlAnimation != null
+                || !mPersistentControlTokens.isEmpty();
+    }
+
+    /**
+     * Returns how tall the opaque portion of the control container is.
+     */
+    public float controlContainerHeight() {
+        return mControlContainerHeight;
+    }
+
+    private float rendererContentOffset() {
+        if (!mEnabled) return mControlContainerHeight;
+        return mRendererContentOffset;
+    }
+
+    private float rendererControlOffset() {
+        if (!mEnabled) return 0;
+        return mRendererControlOffset;
+    }
+
+    /**
+     * @return The visible offset of the content from the top of the screen.
+     */
+    public float getVisibleContentOffset() {
+        if (!mEnabled) return 0;
+        return mControlContainerHeight + getControlOffset();
+    }
+
+    /**
+     * @param listener The {@link FullscreenListener} to be notified of fullscreen changes.
+     */
+    public void addListener(FullscreenListener listener) {
+        if (!mListeners.contains(listener)) mListeners.add(listener);
+    }
+
+    /**
+     * @param listener The {@link FullscreenListener} to no longer be notified of fullscreen
+     *                 changes.
+     */
+    public void removeListener(FullscreenListener listener) {
+        mListeners.remove(listener);
+    }
+
+    /**
+     * Updates the content view's viewport size to have it render the content correctly.
+     *
+     * @param viewCore The ContentViewCore to update.
+     */
+    public void updateContentViewViewportSize(ContentViewCore viewCore) {
+        if (!mEnabled || viewCore == null) return;
+        if (mInGesture || mContentViewScrolling) return;
+
+        // Update content viewport size only when the top controls are not animating.
+        int contentOffset = (int) rendererContentOffset();
+        if (contentOffset != 0 && contentOffset != mControlContainerHeight) return;
+        viewCore.setTopControlsHeight(mControlContainerHeight, contentOffset > 0);
+    }
+
+    @Override
+    public void updateContentViewChildrenState() {
+        ContentViewCore contentViewCore = getActiveContentViewCore();
+        if (contentViewCore == null || !mEnabled) return;
+        ViewGroup view = contentViewCore.getContainerView();
+
+        float topViewsTranslation = (getControlOffset() + mControlContainerHeight);
+        applyTranslationToTopChildViews(view, topViewsTranslation);
+        applyMarginToFullChildViews(view, topViewsTranslation);
+        updateContentViewViewportSize(contentViewCore);
+    }
+
+    /**
+     * Utility routine for ensuring visibility updates are synchronized with
+     * animation, preventing message loop stalls due to untimely invalidation.
+     */
+    private void scheduleVisibilityUpdate() {
+        final int desiredVisibility = shouldShowAndroidControls() ? View.VISIBLE : View.INVISIBLE;
+        if (mControlContainer.getVisibility() == desiredVisibility) return;
+        mControlContainer.removeCallbacks(mUpdateVisibilityRunnable);
+        ApiCompatibilityUtils.postOnAnimation(mControlContainer, mUpdateVisibilityRunnable);
+    }
+
+    private void updateVisuals() {
+        if (!mEnabled) return;
+
+        TraceEvent.begin("FullscreenManager:updateVisuals");
+
+        float offset = getControlOffset();
+        if (Float.compare(mPreviousControlOffset, offset) != 0) {
+            mPreviousControlOffset = offset;
+            getHtmlApiHandler().updateBubblePosition();
+
+            scheduleVisibilityUpdate();
+            if (shouldShowAndroidControls()) mControlContainer.setTranslationY(getControlOffset());
+
+            // In ICS, the toolbar can appear clipped when compositor content is not being drawn
+            // beneath it (at the top of the page, during side swipe).  Requesting a layout clears
+            // up the issue (see crbug.com/172631).
+            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
+                if (!mHandler.hasMessages(MSG_ID_CONTROLS_REQUEST_LAYOUT)) {
+                    mHandler.sendEmptyMessage(MSG_ID_CONTROLS_REQUEST_LAYOUT);
+                }
+            }
+            for (int i = 0; i < mListeners.size(); i++) {
+                mListeners.get(i).onVisibleContentOffsetChanged(getVisibleContentOffset());
+            }
+        }
+
+        final ContentViewCore contentViewCore = getActiveContentViewCore();
+        if (contentViewCore != null && offset == -mControlContainerHeight
+                && mIsEnteringPersistentModeState) {
+            getHtmlApiHandler().enterFullscreen(contentViewCore);
+            mIsEnteringPersistentModeState = false;
+        }
+
+        updateContentViewChildrenState();
+
+        float contentOffset = getContentOffset();
+        if (Float.compare(mPreviousContentOffset, contentOffset) != 0) {
+            for (int i = 0; i < mListeners.size(); i++) {
+                mListeners.get(i).onContentOffsetChanged(contentOffset);
+            }
+            mPreviousContentOffset = contentOffset;
+        }
+
+        TraceEvent.end("FullscreenManager:updateVisuals");
+    }
+
+    /**
+     * @param hide Whether or not to force the top controls Android view to hide.  If this is
+     *             {@code false} the top controls Android view will show/hide based on position, if
+     *             it is {@code true} the top controls Android view will always be hidden.
+     */
+    public void setHideTopControlsAndroidView(boolean hide) {
+        if (mTopControlsAndroidViewHidden == hide) return;
+        mTopControlsAndroidViewHidden = hide;
+        scheduleVisibilityUpdate();
+    }
+
+    private boolean shouldShowAndroidControls() {
+        if (mTopControlsAndroidViewHidden) return false;
+
+        boolean showControls = getControlOffset() == 0;
+        ContentViewCore contentViewCore = getActiveContentViewCore();
+        if (contentViewCore == null) return showControls;
+        ViewGroup contentView = contentViewCore.getContainerView();
+
+        for (int i = 0; i < contentView.getChildCount(); i++) {
+            View child = contentView.getChildAt(i);
+            if (!(child.getLayoutParams() instanceof FrameLayout.LayoutParams)) continue;
+
+            FrameLayout.LayoutParams layoutParams =
+                    (FrameLayout.LayoutParams) child.getLayoutParams();
+            if (Gravity.TOP == (layoutParams.gravity & Gravity.FILL_VERTICAL)) {
+                showControls = true;
+                break;
+            }
+        }
+
+        showControls |= !mPersistentControlTokens.isEmpty();
+
+        return showControls;
+    }
+
+    private void applyMarginToFullChildViews(ViewGroup contentView, float margin) {
+        for (int i = 0; i < contentView.getChildCount(); i++) {
+            View child = contentView.getChildAt(i);
+            if (!(child.getLayoutParams() instanceof FrameLayout.LayoutParams)) continue;
+            FrameLayout.LayoutParams layoutParams =
+                    (FrameLayout.LayoutParams) child.getLayoutParams();
+
+            if (layoutParams.height == LayoutParams.MATCH_PARENT
+                    && layoutParams.topMargin != (int) margin) {
+                layoutParams.topMargin = (int) margin;
+                child.requestLayout();
+                TraceEvent.instant("FullscreenManager:child.requestLayout()");
+            }
+        }
+    }
+
+    private void applyTranslationToTopChildViews(ViewGroup contentView, float translation) {
+        for (int i = 0; i < contentView.getChildCount(); i++) {
+            View child = contentView.getChildAt(i);
+            if (!(child.getLayoutParams() instanceof FrameLayout.LayoutParams)) continue;
+
+            FrameLayout.LayoutParams layoutParams =
+                    (FrameLayout.LayoutParams) child.getLayoutParams();
+            if (Gravity.TOP == (layoutParams.gravity & Gravity.FILL_VERTICAL)) {
+                child.setTranslationY(translation);
+                TraceEvent.instant("FullscreenManager:child.setTranslationY()");
+            }
+        }
+    }
+
+    private ContentViewCore getActiveContentViewCore() {
+        Tab tab = getTabModelSelector().getCurrentTab();
+        return tab != null ? tab.getContentViewCore() : null;
+    }
+
+    @Override
+    public void setPositionsForTabToNonFullscreen() {
+        setPositionsForTab(0, mControlContainerHeight);
+    }
+
+    @Override
+    public void setPositionsForTab(float controlsOffset, float contentOffset) {
+        if (!mEnabled) return;
+        float rendererControlOffset =
+                Math.round(Math.max(controlsOffset, -mControlContainerHeight));
+        float rendererContentOffset = Math.min(
+                Math.round(contentOffset), rendererControlOffset + mControlContainerHeight);
+
+        if (Float.compare(rendererControlOffset, mRendererControlOffset) == 0
+                && Float.compare(rendererContentOffset, mRendererContentOffset) == 0) {
+            return;
+        }
+
+        mRendererControlOffset = rendererControlOffset;
+        mRendererContentOffset = rendererContentOffset;
+        updateControlOffset();
+
+        if (mControlAnimation == null) updateVisuals();
+    }
+
+    /**
+     * @param e The dispatched motion event
+     * @return Whether or not this motion event is in the top control container area and should be
+     *         consumed.
+     */
+    public boolean onInterceptMotionEvent(MotionEvent e) {
+        return mEnabled && e.getY() < getControlOffset() + mControlContainerHeight
+                && !mTopControlsAndroidViewHidden;
+    }
+
+    /**
+     * Notifies the fullscreen manager that a motion event has occurred.
+     * @param e The dispatched motion event.
+     */
+    public void onMotionEvent(MotionEvent e) {
+        if (!mEnabled) return;
+        int eventAction = e.getActionMasked();
+        if (eventAction == MotionEvent.ACTION_DOWN
+                || eventAction == MotionEvent.ACTION_POINTER_DOWN) {
+            mInGesture = true;
+            getHtmlApiHandler().hideNotificationBubble();
+        } else if (eventAction == MotionEvent.ACTION_CANCEL
+                || eventAction == MotionEvent.ACTION_UP) {
+            mInGesture = false;
+            updateVisuals();
+        }
+    }
+
+    private void update(boolean show) {
+        // On forced show/hide, reset the flags that may suppress ContentView resize.
+        // As this method is also called when tab is switched, this also cleanup the scrolling
+        // flag set based on the previous ContentView's scrolling state.
+        mInGesture = false;
+        mContentViewScrolling = false;
+
+        if (!mEnabled) return;
+
+        if (show) mCurrentShowTime = SystemClock.uptimeMillis();
+
+        boolean postHideMessage = false;
+        if (!show) {
+            if (mControlAnimation != null && mCurrentAnimationIsShowing) {
+                postHideMessage = true;
+            } else {
+                long timeDelta = SystemClock.uptimeMillis() - mCurrentShowTime;
+                animateIfNecessary(false, Math.max(mMinShowNotificationMs - timeDelta, 0));
+            }
+        } else {
+            animateIfNecessary(true, 0);
+            if (mPersistentControlTokens.isEmpty()) postHideMessage = true;
+        }
+
+        mHandler.removeMessages(MSG_ID_HIDE_CONTROLS);
+        if (postHideMessage) {
+            long timeDelta = SystemClock.uptimeMillis() - mCurrentShowTime;
+            mHandler.sendEmptyMessageDelayed(
+                    MSG_ID_HIDE_CONTROLS, Math.max(mMinShowNotificationMs - timeDelta, 0));
+        }
+    }
+
+    private void animateIfNecessary(final boolean show, long startDelay) {
+        if (mControlAnimation != null) {
+            if (!mControlAnimation.isRunning() || mCurrentAnimationIsShowing != show) {
+                mControlAnimation.cancel();
+                mControlAnimation = null;
+            } else {
+                return;
+            }
+        }
+
+        float destination = show ? 0 : -mControlContainerHeight;
+        long duration = (long) (mMaxAnimationDurationMs
+                * Math.abs((destination - getControlOffset()) / mControlContainerHeight));
+        mControlAnimation = ObjectAnimator.ofFloat(this, new ControlsOffsetProperty(), destination);
+        mControlAnimation.addListener(new AnimatorListenerAdapter() {
+            private boolean mCanceled = false;
+
+            @Override
+            public void onAnimationCancel(Animator anim) {
+                mCanceled = true;
+            }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                if (!show && !mCanceled) mBrowserControlOffset = Float.NaN;
+                mControlAnimation = null;
+            }
+        });
+        mControlAnimation.setStartDelay(startDelay);
+        mControlAnimation.setDuration(duration);
+        mControlAnimation.start();
+        mCurrentAnimationIsShowing = show;
+    }
+
+    @Override
+    public void onContentViewScrollingStateChanged(boolean scrolling) {
+        mContentViewScrolling = scrolling;
+        if (!scrolling) updateVisuals();
+    }
+}