Hide fullscreen rotation jank

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

 // 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.tab;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.app.Application;
 import android.content.Context;
@@ skipping 2491 matching lines @@
 
     /**
      * Toggles fullscreen mode and notifies all observers.
      * @param enableFullscreen Whether fullscreen should be enabled.
      */
     public void toggleFullscreenMode(boolean enableFullscreen) {
         if (mFullscreenManager != null) {
             mFullscreenManager.setPersistentFullscreenMode(enableFullscreen);
         }
 
+        // When going into fullscreen, we want to remove any cached thumbnail of the Tab.
+        if (enableFullscreen) {
+            clearThumbnailPlaceholder();
+        }
+
         RewindableIterator<TabObserver> observers = getTabObservers();
         while (observers.hasNext()) {
             observers.next().onToggleFullscreenMode(this, enableFullscreen);
         }
     }
 
     /**
      * Called when offset values related with fullscreen functionality has been changed by the
      * compositor.
      * @param topControlsOffsetY The Y offset of the top controls in physical pixels.
@@ skipping 14 matching lines @@
         if (isShowingSadTab() || isNativePage()) {
             mFullscreenManager.setPositionsForTabToNonFullscreen();
         } else {
             mFullscreenManager.setPositionsForTab(mPreviousTopControlsOffsetY,
                     mPreviousBottomControlsOffsetY, mPreviousContentOffsetY);
         }
         TabModelImpl.setActualTabSwitchLatencyMetricRequired();
     }
 
     /**
+     * Clears the cached thumbnail for this Tab.
+     */
+    public void clearThumbnailPlaceholder() {

[Khushal, 2017/07/12 17:15:39]

You don't need this public function. Use the native function directly in
toggleFullscreenMode?

[steimel, 2017/07/12 18:24:21]

Done.

+        if (mNativeTabAndroid != 0) nativeClearThumbnailPlaceholder(mNativeTabAndroid);
+    }
+
+    /**
      * Push state about whether or not the browser controls can show or hide to the renderer.
      */
     public void updateFullscreenEnabledState() {
         if (isFrozen()) return;
 
         updateBrowserControlsState(
                 getBrowserControlsStateConstraints(), BrowserControlsState.BOTH, true);
 
         if (getContentViewCore() != null && mFullscreenManager != null) {
             getContentViewCore().updateMultiTouchZoomSupport(
@@ skipping 570 matching lines @@
     private native Bitmap nativeGetFavicon(long nativeTabAndroid);
     private native void nativeCreateHistoricalTab(long nativeTabAndroid);
     private native void nativeUpdateBrowserControlsState(
             long nativeTabAndroid, int constraints, int current, boolean animate);
     private native void nativeLoadOriginalImage(long nativeTabAndroid);
     private native long nativeGetBookmarkId(long nativeTabAndroid, boolean onlyEditable);
     private native void nativeSetInterceptNavigationDelegate(long nativeTabAndroid,
             InterceptNavigationDelegate delegate);
     private native void nativeAttachToTabContentManager(long nativeTabAndroid,
             TabContentManager tabContentManager);
+    private native void nativeClearThumbnailPlaceholder(long nativeTabAndroid);
     private native boolean nativeHasPrerenderedUrl(long nativeTabAndroid, String url);
     private native void nativeSetWebappManifestScope(long nativeTabAndroid, String scope);
     private native void nativeEnableEmbeddedMediaExperience(long nativeTabAndroid, boolean enabled);
     private native void nativeAttachDetachedTab(long nativeTabAndroid);
 }