[Paint Preview] Tab integration for startup experiment

This CL implements the integration needed for paint previews to show
on a cold start. This feature is guarded behind an experimental flag
that is only intended for the Canary/Dev channels.

PTAL at the design doc for more context: http://go/fdt-tab-integration

Bug: 1064011
Change-Id: I91bd682f32eccb8e22b27ec026f04079fd6fc250
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231179Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Mehran Mahmoudi <mahmoudi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776229}

chrome/android/chrome_java_sources.gni

@@ -1191,7 +1191,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/page_info/SiteSettingsHelper.java",
   "java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewDemoManager.java",
   "java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewExperiments.java",
-  "java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewInitializer.java",
+  "java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewHelper.java",
   "java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewTabHelper.java",
   "java/src/org/chromium/chrome/browser/paint_preview/TabbedPaintPreviewPlayer.java",
   "java/src/org/chromium/chrome/browser/paint_preview/services/PaintPreviewDemoService.java",

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

@@ -112,7 +112,7 @@ import org.chromium.chrome.browser.omaha.notification.UpdateNotificationControll
 import org.chromium.chrome.browser.omaha.notification.UpdateNotificationControllerFactory;
 import org.chromium.chrome.browser.page_info.ChromePageInfoControllerDelegate;
 import org.chromium.chrome.browser.page_info.ChromePermissionParamsListBuilderDelegate;
-import org.chromium.chrome.browser.paint_preview.PaintPreviewInitializer;
+import org.chromium.chrome.browser.paint_preview.PaintPreviewHelper;
 import org.chromium.chrome.browser.partnercustomizations.PartnerBrowserCustomizations;
 import org.chromium.chrome.browser.preferences.Pref;
 import org.chromium.chrome.browser.preferences.PrefServiceBridge;
@@ -612,7 +612,7 @@ public abstract class ChromeActivity<C extends ChromeActivityComponent>
         mIncognitoTabCreator = tabCreators.second;
 
         OfflinePageUtils.observeTabModelSelector(this, mTabModelSelector);
-        PaintPreviewInitializer.observeTabModelSelector(this, mTabModelSelector);
+        PaintPreviewHelper.observeTabModelSelector(this, mTabModelSelector);
 
         if (mTabModelSelectorTabObserver != null) mTabModelSelectorTabObserver.destroy();
 

chrome/android/java/src/org/chromium/chrome/browser/app/appmenu/AppMenuPropertiesDelegateImpl.java

@@ -635,7 +635,7 @@ public class AppMenuPropertiesDelegateImpl implements AppMenuPropertiesDelegate
 
         boolean itemVisible = canShowRequestDesktopSite
                 && (!isChromeScheme || currentTab.isNativePage())
-                && !shouldShowReaderModePrefs(currentTab);
+                && !shouldShowReaderModePrefs(currentTab) && currentTab.getWebContents() != null;
         requestMenuRow.setVisible(itemVisible);
         if (!itemVisible) return;
 

chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchTabHelper.java

@@ -106,7 +106,7 @@ public class ContextualSearchTabHelper
     public void onContentChanged(Tab tab) {
         // Native initialization happens after a page loads or content is changed to ensure profile
         // is initialized.
-        if (mNativeHelper == 0) {
+        if (mNativeHelper == 0 && tab.getWebContents() != null) {
             mNativeHelper = ContextualSearchTabHelperJni.get().init(
                     ContextualSearchTabHelper.this, Profile.fromWebContents(tab.getWebContents()));
         }

chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java

@@ -202,8 +202,9 @@ public class ReaderModeManager extends EmptyTabObserver implements UserData {
         }
 
         // Make sure there is a WebContentsObserver on this tab's WebContents.
-        if (mWebContentsObserver == null) mWebContentsObserver = createWebContentsObserver();
-
+        if (mWebContentsObserver == null && mTab.getWebContents() != null) {
+            mWebContentsObserver = createWebContentsObserver();
+        }
         tryShowingInfoBar();
     }
 

chrome/android/java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewInitializer.java → chrome/android/java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewHelper.java

@@ -8,13 +8,14 @@ import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.multiwindow.MultiWindowUtils;
 import org.chromium.chrome.browser.paint_preview.services.PaintPreviewTabServiceFactory;
+import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.EmptyTabModelSelectorObserver;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 
 /**
  * Handles initialization of the Paint Preview tab observers.
  */
-public class PaintPreviewInitializer {
+public class PaintPreviewHelper {
     /**
      * Observes a {@link TabModelSelector} to monitor for initialization completion.
      * @param activity The ChromeActivity that corresponds to the tabModelSelector.
@@ -39,4 +40,20 @@ public class PaintPreviewInitializer {
             }
         });
     }
+
+    /**
+     * Attemps to display the Paint Preview representation of for the given Tab.
+     * @param onShown The callback for when the Paint Preview is shown.
+     * @param onDismissed The callback for when the Paint Preview is dismissed.
+     * @return Whether the Paint Preview started to initialize or is already initializating.
+     * Note that if the Paint Preview is already showing, this will return false.
+     */
+    public static boolean showPaintPreviewOnRestore(
+            Tab tab, Runnable onShown, Runnable onDismissed) {
+        if (!ChromeFeatureList.isEnabled(ChromeFeatureList.PAINT_PREVIEW_SHOW_ON_STARTUP)) {
+            return false;
+        }
+
+        return TabbedPaintPreviewPlayer.get(tab).maybeShow(onShown, onDismissed);
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/paint_preview/TabbedPaintPreviewPlayer.java

@@ -32,6 +32,7 @@ public class TabbedPaintPreviewPlayer implements TabViewProvider, UserData {
     private PlayerManager mPlayerManager;
     private Runnable mOnShown;
     private Runnable mOnDismissed;
+    private Boolean mInitializing;
 
     public static TabbedPaintPreviewPlayer get(Tab tab) {
         if (tab.getUserDataHost().getUserData(USER_DATA_KEY) == null) {
@@ -46,24 +47,27 @@ public class TabbedPaintPreviewPlayer implements TabViewProvider, UserData {
     }
 
     /**
-     * Shows a Paint Preview for the provided tab if it exists.
+     * Shows a Paint Preview for the provided tab if it exists and has not been displayed for this
+     * Tab before.
      * @param onShown The callback for when the Paint Preview is shown.
      * @param onDismissed The callback for when the Paint Preview is dismissed.
-     * @return a boolean indicating whether a Paint Preview exists for the tab.
+     * @return Whether the Paint Preview started to initialize or is already initializating.
+     * Note that if the Paint Preview is already showing, this will return false.
      */
-    public boolean showIfExists(@Nullable Runnable onShown, @Nullable Runnable onDismissed) {
-        if (isShowing()) return true;
+    public boolean maybeShow(@Nullable Runnable onShown, @Nullable Runnable onDismissed) {
+        if (mInitializing != null) return mInitializing;
 
         // Check if a capture exists. This is a quick check using a cache.
         boolean hasCapture = mPaintPreviewTabService.hasCaptureForTab(mTab.getId());
-        mOnShown = onShown;
-        mOnDismissed = onDismissed;
+        mInitializing = hasCapture;
         if (hasCapture) {
             mPlayerManager = new PlayerManager(mTab.getUrl(), mTab.getContext(),
                     mPaintPreviewTabService, String.valueOf(mTab.getId()), this::onLinkClicked,
                     this::removePaintPreview,
                     () -> TabViewManager.get(mTab).addTabViewProvider(this),
                     TabThemeColorHelper.getBackgroundColor(mTab), this::removePaintPreview);
+            mOnShown = onShown;
+            mOnDismissed = onDismissed;
         }
 
         return hasCapture;
@@ -74,13 +78,14 @@ public class TabbedPaintPreviewPlayer implements TabViewProvider, UserData {
      * nothing if there is no view showing.
      */
     private void removePaintPreview() {
+        mOnShown = null;
+        mOnDismissed = null;
+        mInitializing = false;
         if (mTab == null || mPlayerManager == null) return;
 
         TabViewManager.get(mTab).removeTabViewProvider(this);
         mPlayerManager.destroy();
         mPlayerManager = null;
-        mOnShown = null;
-        mOnDismissed = null;
     }
 
     public boolean isShowing() {
@@ -106,6 +111,7 @@ public class TabbedPaintPreviewPlayer implements TabViewProvider, UserData {
 
     @Override
     public void onShown() {
+        mInitializing = false;
         if (mOnShown != null) mOnShown.run();
     }
 

chrome/android/java/src/org/chromium/chrome/browser/tab/DEPS

@@ -51,6 +51,7 @@ specific_include_rules = {
     "+chrome/android/java/src/org/chromium/chrome/browser/native_page/NativePage.java",
     "+chrome/android/java/src/org/chromium/chrome/browser/native_page/NativePageAssassin.java",
     "+chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageUtils.java",
+    "+chrome/android/java/src/org/chromium/chrome/browser/paint_preview/PaintPreviewHelper.java",
     "+chrome/android/java/src/org/chromium/chrome/browser/prerender/ExternalPrerenderHandler.java",
     "+chrome/android/java/src/org/chromium/chrome/browser/rlz/RevenueStats.java",
     "+chrome/android/java/src/org/chromium/chrome/browser/night_mode",

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

@@ -34,6 +34,7 @@ import org.chromium.chrome.browser.contextmenu.ContextMenuPopulator;
 import org.chromium.chrome.browser.native_page.NativePageAssassin;
 import org.chromium.chrome.browser.night_mode.NightModeUtils;
 import org.chromium.chrome.browser.offlinepages.OfflinePageUtils;
+import org.chromium.chrome.browser.paint_preview.PaintPreviewHelper;
 import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
 import org.chromium.chrome.browser.rlz.RevenueStats;
 import org.chromium.chrome.browser.tab.TabState.WebContentsState;
@@ -618,7 +619,6 @@ public class TabImpl implements Tab, TabObscuringHandler.Observer {
             updateInteractableState();
 
             loadIfNeeded();
-            assert !isFrozen();
 
             if (getWebContents() != null) getWebContents().onShow();
 
@@ -1395,6 +1395,14 @@ public class TabImpl implements Tab, TabObscuringHandler.Observer {
      * history load are used.
      */
     private final void restoreIfNeeded() {
+        // Attempts to display the Paint Preview representation of this Tab instead of fully
+        // restoring. Please note that this is behind an experimental flag.
+        if (isFrozen()
+                && PaintPreviewHelper.showPaintPreviewOnRestore(
+                        this, () -> restoreIfNeeded(), () -> restoreIfNeeded())) {
+            return;
+        }
+
         try {
             TraceEvent.begin("Tab.restoreIfNeeded");
             // Restore is needed for a tab that is loaded for the first time. WebContents will