Delete more document mode specific code.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
index cf139468c39267ee0561e0639ca60a616ae19cfa..8942aa23d1d6bf5cb3a8d6b8acbe5e42f1ec258a 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
@@ -1670,14 +1670,7 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
         }
 
         mUmaSessionStats.updateMetricsServiceState();
-        // In DocumentMode we need the application-level TabModelSelector instead of per
-        // activity which only manages a single tab.
-        if (FeatureUtilities.isDocumentMode(this)) {
-            mUmaSessionStats.startNewSession(
-                    ChromeApplication.getDocumentTabModelSelector());
-        } else {
-            mUmaSessionStats.startNewSession(getTabModelSelector());
-        }
+        mUmaSessionStats.startNewSession(getTabModelSelector());
     }
 
     /**