Upstream WarmupManager.

BUG=449163

Review URL: https://codereview.chromium.org/854843002

Cr-Commit-Position: refs/heads/master@{#315300}

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

+// Copyright 2015 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;
+
+import android.content.Context;
+import android.view.ContextThemeWrapper;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.FrameLayout;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
+import org.chromium.chrome.browser.profiles.Profile;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * This class is a singleton that holds utilities for warming up Chrome and prerendering urls
+ * without creating the Activity.
+ */
+public final class WarmupManager {
+    private static WarmupManager sWarmupManager;
+
+    private WebContents mPrerenderedWebContents;
+    private boolean mPrerendered;
+    private ViewGroup mMainView;
+    private ExternalPrerenderHandler mExternalPrerenderHandler;
+
+    /**
+     * @return The singleton instance for the WarmupManager, creating one if necessary.
+     */
+    public static WarmupManager getInstance() {
+        ThreadUtils.assertOnUiThread();
+        if (sWarmupManager == null) sWarmupManager = new WarmupManager();
+        return sWarmupManager;
+    }
+
+    private WarmupManager() {
+    }
+
+    /**
+     * Check whether prerender manager has the given url prerendered. This also works with
+     * redirected urls.
+     *
+     * Uses the last used profile.
+     *
+     * @param url The url to check.
+     * @return Whether the given url has been prerendered.
+     */
+    public boolean hasPrerenderedUrl(String url) {
+        return hasAnyPrerenderedUrl() && ExternalPrerenderHandler.hasPrerenderedUrl(
+                Profile.getLastUsedProfile(), url, mPrerenderedWebContents);
+    }
+
+    /**
+     * @return Whether any url has been prerendered.
+     */
+    public boolean hasAnyPrerenderedUrl() {
+        return mPrerendered;
+    }
+
+    /**
+     * @return The prerendered {@link WebContents} clearing out the reference WarmupManager owns.
+     */
+    public WebContents takePrerenderedWebContents() {
+        WebContents prerenderedWebContents = mPrerenderedWebContents;
+        assert (mPrerenderedWebContents != null);
+        mPrerenderedWebContents = null;
+        return prerenderedWebContents;
+    }
+
+    /**
+     * Prerenders the given url using the prerender_manager.
+     *
+     * Uses the last used profile.
+     *
+     * @param url The url to prerender.
+     * @param referrer The referrer url to be used while prerendering
+     * @param widthPix The width in pixels to which the page should be prerendered.
+     * @param heightPix The height in pixels to which the page should be prerendered.
+     */
+    public void prerenderUrl(final String url, final String referrer,
+            final int widthPix, final int heightPix) {
+        clearWebContentsIfNecessary();
+        if (mExternalPrerenderHandler == null) {
+            mExternalPrerenderHandler = new ExternalPrerenderHandler();
+        }
+
+        mPrerenderedWebContents = mExternalPrerenderHandler.addPrerender(
+                Profile.getLastUsedProfile(), url, referrer, widthPix, heightPix);
+        if (mPrerenderedWebContents != null) mPrerendered = true;
+    }
+
+    /**
+     * Inflates and constructs the view hierarchy that the app will use.
+     * @param baseContext The base context to use for creating the ContextWrapper.
+     * @param themeId Id of the main theme to use in the inflated views.
+     * @param layoutId Id of the layout to inflate.
+     */
+    public void initializeViewHierarchy(Context baseContext, int themeId, int layoutId) {
+        ContextThemeWrapper context = new ContextThemeWrapper(baseContext, themeId);
+        FrameLayout contentHolder = new FrameLayout(context);
+        mMainView = (ViewGroup) LayoutInflater.from(context).inflate(layoutId, contentHolder);
+    }
+
+    /**
+     * Transfers all the children in the view hierarchy to the giving ViewGroup as child.
+     * @param contentView The parent ViewGroup to use for the transfer.
+     */
+    public void transferViewHierarchyTo(ViewGroup contentView) {
+        ViewGroup viewHierarchy = takeMainView();
+        if (viewHierarchy == null) return;
+        while (viewHierarchy.getChildCount() > 0) {
+            View currentChild = viewHierarchy.getChildAt(0);
+            viewHierarchy.removeView(currentChild);
+            contentView.addView(currentChild);
+        }
+    }
+
+    /**
+     * Destroys the native WebContents instance the WarmupManager currently holds onto.
+     */
+    public void clearWebContentsIfNecessary() {
+        mPrerendered = false;
+        if (mPrerenderedWebContents == null) return;
+
+        mPrerenderedWebContents.destroy();
+        mPrerenderedWebContents = null;
+    }
+
+    /**
+     * Cancel the current prerender.
+     */
+    public void cancelCurrentPrerender() {
+        clearWebContentsIfNecessary();
+        if (mExternalPrerenderHandler == null) return;
+
+        mExternalPrerenderHandler.cancelCurrentPrerender();
+    }
+
+    /**
+     * @return Whether the view hierarchy has been prebuilt.
+     */
+    public boolean hasBuiltViewHierarchy() {
+        return mMainView != null;
+    }
+
+    /**
+     * @return The prebuilt view hierarchy and clears the reference WarmupManager owns.
+     */
+    private ViewGroup takeMainView() {
+        ViewGroup mainView = mMainView;
+        mMainView = null;
+        return mainView;
+    }
+}