Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/overlays/strip/TabLoadTracker.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.compositor.overlays.strip;
+
+import android.os.Handler;
+
+/**
+ * {@code TabLoadTracker} is used to handle tracking whether or not to visually show if a tab is
+ * loading or not.
+ */
+public class TabLoadTracker {
+    private static final long LOAD_FINISHED_VISUAL_DELAY_MS = 100;
+
+    private final Handler mHandler = new Handler();
+
+    // Callback Tracking State
+    private final int mId;
+    private final TabLoadTrackerCallback mCallback;
+
+    // Internal Loading State
+    private boolean mLoading;
+    private boolean mPageLoading;
+
+    /**
+     * The callback object to be notified of when the loading state changes.
+     */
+    public interface TabLoadTrackerCallback {
+        /**
+         * Called when the loading state tracked by this tab should visually change.
+         * @param id The id of the Tab.
+         */
+        public void loadStateChanged(int id);
+    }
+
+    /**
+     * Creates an instance of the {@link TabLoadTracker} class.
+     * @param id       The id of the tab to track for callback purposes.
+     * @param callback The {@link TabLoadTrackerCallback} to notify on loading state changes.
+     */
+    public TabLoadTracker(int id, TabLoadTrackerCallback callback) {
+        mId = id;
+        mCallback = callback;
+    }
+
+    /**
+     * Called when this tab has started loading.
+     */
+    public void pageLoadingStarted() {
+        if (!mPageLoading) {
+            mPageLoading = true;
+            mCallback.loadStateChanged(mId);
+        }
+        mHandler.removeCallbacks(mPageLoadFinishedRunnable);
+    }
+
+    /**
+     * Called when this tab has finished loading.
+     */
+    public void pageLoadingFinished() {
+        if (!mPageLoading) return;
+        mHandler.removeCallbacks(mPageLoadFinishedRunnable);
+        mHandler.postDelayed(mPageLoadFinishedRunnable, LOAD_FINISHED_VISUAL_DELAY_MS);
+    }
+
+    /**
+     * Called when this tab has started loading resources.
+     */
+    public void loadingStarted() {
+        if (!mLoading) {
+            mLoading = true;
+            mCallback.loadStateChanged(mId);
+        }
+        mHandler.removeCallbacks(mLoadFinishedRunnable);
+    }
+
+    /**
+     * Called when this tab has finished loading resources.
+     */
+    public void loadingFinished() {
+        if (!mLoading) return;
+        mHandler.removeCallbacks(mLoadFinishedRunnable);
+        mHandler.postDelayed(mLoadFinishedRunnable, LOAD_FINISHED_VISUAL_DELAY_MS);
+    }
+
+    /**
+     * @return Whether or not this tab should be visually represented as loading.
+     */
+    public boolean isLoading() {
+        return mLoading || mPageLoading;
+    }
+
+    private Runnable mLoadFinishedRunnable = new Runnable() {
+        @Override
+        public void run() {
+            mLoading = false;
+            mCallback.loadStateChanged(mId);
+        }
+    };
+
+    private Runnable mPageLoadFinishedRunnable = new Runnable() {
+        @Override
+        public void run() {
+            mPageLoading = false;
+            mCallback.loadStateChanged(mId);
+        }
+    };
+}