Using UrlConstants instead of hardcoded values in few places

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java
index ce805cf87612b51cad8c8cd5c00e7dbc28d784dd..bc18ba904af967359110647390fa6c5b0bc3f266 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersistentStore.java
@@ -26,6 +26,7 @@ import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.browser.TabState;
+import org.chromium.chrome.browser.UrlConstants;
 import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
 import org.chromium.chrome.browser.ntp.NewTabPage;
 import org.chromium.chrome.browser.tab.Tab;
@@ -1305,7 +1306,7 @@ public class TabPersistentStore extends TabPersister {
 
     private boolean isTabUrlContentScheme(Tab tab) {
         String url = tab.getUrl();
-        return url != null && url.startsWith("content");
+        return url != null && url.startsWith(UrlConstants.CONTENT_SCHEME);
     }
 
     /**