[Offline pages] Expose offline pages URL related methods in java code.

chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java

Index: chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java
index d3b6c572346c76e884cf552dc63072df23475f7c..ab6fe1d4ba35796e35ec41332909d9319cb06fa6 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java
@@ -22,6 +22,7 @@ import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.UrlConstants;
+import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 import org.chromium.chrome.browser.util.IntentUtils;
 import org.chromium.chrome.browser.util.UrlUtilities;
 import org.chromium.ui.base.PageTransition;
@@ -169,6 +170,17 @@ public class ExternalNavigationHandler {
             return OverrideUrlLoadingResult.NO_OVERRIDE;
         }
 
+        // If accessing a file URL, which points to an offline copy of an offline page, there
+        // is no need to override the navigation.
+        if (OfflinePageBridge.isEnabled()) {
+            OfflinePageBridge offlinePageBridge =
+                    new OfflinePageBridge(params.getTab().getProfile());
+            if (offlinePageBridge.isOfflinePageUrl(params.getUrl())) {
+                return OverrideUrlLoadingResult.NO_OVERRIDE;
+            }
+            offlinePageBridge.destroy();
+        }
+
         // If accessing a file URL, ensure that the user has granted the necessary file access
         // to Chrome.  This check should happen for reloads, navigations, etc..., which is why
         // it occurs before the subsequent blocks.