Unify how OfflinePages is called

* Provide a single jumping off point that avoids memory leaks when using
  the OfflinePageDownloadBridge from the menus.

* Provide a single function for determining whether the offline pages button
  should be clickable.

BUG=616324

Review-Url: https://codereview.chromium.org/2322773002
Cr-Commit-Position: refs/heads/master@{#417130}

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

@@ -90,7 +90,6 @@ import org.chromium.chrome.browser.nfc.BeamController;
 import org.chromium.chrome.browser.nfc.BeamProvider;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 import org.chromium.chrome.browser.offlinepages.OfflinePageUtils;
-import org.chromium.chrome.browser.offlinepages.downloads.OfflinePageDownloadBridge;
 import org.chromium.chrome.browser.omaha.UpdateMenuItemHelper;
 import org.chromium.chrome.browser.pageinfo.WebsiteSettingsPopup;
 import org.chromium.chrome.browser.partnercustomizations.PartnerBrowserCustomizations;
@@ -1563,13 +1562,8 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
             addOrEditBookmark(currentTab);
             RecordUserAction.record("MobileMenuAddToBookmarks");
         } else if (id == R.id.offline_page_id) {
-            final OfflinePageDownloadBridge bridge =
-                    new OfflinePageDownloadBridge(currentTab.getProfile());
-            bridge.startDownload(currentTab);
-            bridge.destroy();
+            DownloadUtils.downloadOfflinePage(this, currentTab);
             RecordUserAction.record("MobileMenuDownloadPage");
-            DownloadUtils.recordDownloadPageMetrics(currentTab);
-            DownloadUtils.showDownloadStartToast(this);
         } else if (id == R.id.reload_menu_id) {
             if (currentTab.isLoading()) {
                 currentTab.stopLoading();

chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuPropertiesDelegate.java

@@ -16,6 +16,7 @@ import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.ShortcutHelper;
 import org.chromium.chrome.browser.UrlConstants;
 import org.chromium.chrome.browser.bookmarks.BookmarkBridge;
+import org.chromium.chrome.browser.download.DownloadUtils;
 import org.chromium.chrome.browser.multiwindow.MultiWindowUtils;
 import org.chromium.chrome.browser.omaha.UpdateMenuItemHelper;
 import org.chromium.chrome.browser.preferences.ManagedPreferencesUtils;
@@ -110,10 +111,9 @@ public class AppMenuPropertiesDelegate {
                 MenuItem offlineMenuItem = menu.findItem(R.id.offline_page_id);
                 if (offlineMenuItem != null) {
                     if (ChromeFeatureList.isEnabled("DownloadsUi")) {
-                        boolean isValidTab = !currentTab.isOfflinePage()
-                                && !currentTab.isShowingErrorPage()
-                                && !currentTab.isShowingInterstitialPage();
-                        offlineMenuItem.setEnabled(!isChromeScheme && !isIncognito && isValidTab);
+                        offlineMenuItem.setEnabled(
+                                DownloadUtils.isAllowedToDownloadPage(currentTab));
+
                         Drawable drawable = offlineMenuItem.getIcon();
                         if (drawable != null) {
                             int iconTint = ApiCompatibilityUtils.getColor(

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadUtils.java

@@ -15,6 +15,8 @@ import org.chromium.chrome.browser.ChromeTabbedActivity;
 import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.UrlConstants;
 import org.chromium.chrome.browser.download.ui.BackendProvider;
+import org.chromium.chrome.browser.download.ui.BackendProvider.DownloadDelegate;
+import org.chromium.chrome.browser.offlinepages.downloads.OfflinePageDownloadBridge;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabModel.TabLaunchType;
 import org.chromium.chrome.browser.tabmodel.document.TabDelegate;
@@ -98,4 +100,39 @@ public class DownloadUtils {
         RecordUserAction.record(
                 "Android.DownloadManager.CheckForExternallyRemovedItems");
     }
+
+    /**
+     * Trigger the download of an Offline Page.
+     * @param context Context to pull resources from.
+     */
+    public static void downloadOfflinePage(Context context, Tab tab) {
+        final OfflinePageDownloadBridge bridge = new OfflinePageDownloadBridge(tab.getProfile());
+        bridge.startDownload(tab);
+        bridge.destroy();
+        DownloadUtils.recordDownloadPageMetrics(tab);
+        DownloadUtils.showDownloadStartToast(context);
+    }
+
+    /**
+     * Whether the user should be allowed to download the current page.
+     * @param tab Tab displaying the page that will be downloaded.
+     * @return    Whether the "Download Page" button should be enabled.
+     */
+    public static boolean isAllowedToDownloadPage(Tab tab) {
+        if (tab == null) return false;
+
+        // Don't allow downloading internal pages.
+        if (tab.getUrl().startsWith(UrlConstants.CHROME_SCHEME)) return false;
+        if (tab.getUrl().startsWith(UrlConstants.CHROME_NATIVE_SCHEME)) return false;
+        if (tab.isShowingErrorPage()) return false;
+        if (tab.isShowingInterstitialPage()) return false;
+
+        // Don't allow re-downloading the currently displayed offline page.
+        if (tab.isOfflinePage()) return false;
+
+        // Offline pages isn't supported in Incognito.
+        if (tab.isIncognito()) return false;
+
+        return true;
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/omnibox/LocationBarTablet.java

@@ -19,7 +19,7 @@ import android.view.WindowManager;
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeFeatureList;
-import org.chromium.chrome.browser.UrlConstants;
+import org.chromium.chrome.browser.download.DownloadUtils;
 import org.chromium.chrome.browser.ntp.NewTabPage;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.toolbar.ToolbarTablet;
@@ -568,13 +568,7 @@ public class LocationBarTablet extends LocationBarLayout {
 
     private boolean isSaveOfflineButtonEnabled() {
         if (mToolbarDataProvider == null) return false;
-        Tab tab = mToolbarDataProvider.getTab();
-        if (tab == null) return false;
-        boolean isChromeScheme = tab.getUrl().startsWith(UrlConstants.CHROME_SCHEME)
-                || tab.getUrl().startsWith(UrlConstants.CHROME_NATIVE_SCHEME);
-        boolean isValidTab = !tab.isOfflinePage() && !tab.isShowingErrorPage()
-                             && !tab.isShowingInterstitialPage();
-        return !isChromeScheme && isValidTab;
+        return DownloadUtils.isAllowedToDownloadPage(mToolbarDataProvider.getTab());
     }
 
     private boolean shouldShowPageActionButtons() {

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarTablet.java

@@ -23,7 +23,6 @@ import org.chromium.chrome.browser.NavigationPopup;
 import org.chromium.chrome.browser.device.DeviceClassManager;
 import org.chromium.chrome.browser.download.DownloadUtils;
 import org.chromium.chrome.browser.ntp.NewTabPage;
-import org.chromium.chrome.browser.offlinepages.downloads.OfflinePageDownloadBridge;
 import org.chromium.chrome.browser.omnibox.LocationBar;
 import org.chromium.chrome.browser.omnibox.LocationBarTablet;
 import org.chromium.chrome.browser.partnercustomizations.HomepageManager;
@@ -308,13 +307,8 @@ public class ToolbarTablet extends ToolbarLayout implements OnClickListener {
                 mTabSwitcherListener.onClick(mAccessibilitySwitcherButton);
             }
         } else if (mSaveOfflineButton == v) {
-            Tab tab = getToolbarDataProvider().getTab();
-            OfflinePageDownloadBridge bridge = new OfflinePageDownloadBridge(tab.getProfile());
-            bridge.startDownload(tab);
-            bridge.destroy();
+            DownloadUtils.downloadOfflinePage(getContext(), getToolbarDataProvider().getTab());
             RecordUserAction.record("MobileToolbarDownloadPage");
-            DownloadUtils.recordDownloadPageMetrics(tab);
-            DownloadUtils.showDownloadStartToast(getContext());
         }
     }