✈ Remove unnecessary flag and DocumentModeManager.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/DocumentModeAssassin.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/DocumentModeAssassin.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/DocumentModeAssassin.java
index f3328c49529c66d67ec810cdaf48f0013d465d98..d50dba9df10c5d09c348553f1afb53bd0a584fe1 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/DocumentModeAssassin.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/DocumentModeAssassin.java
@@ -24,7 +24,6 @@ import org.chromium.chrome.browser.document.DocumentActivity;
 import org.chromium.chrome.browser.document.DocumentUtils;
 import org.chromium.chrome.browser.document.IncognitoDocumentActivity;
 import org.chromium.chrome.browser.incognito.IncognitoNotificationManager;
-import org.chromium.chrome.browser.preferences.DocumentModeManager;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.TabPersistentStore.TabModelMetadata;
 import org.chromium.chrome.browser.tabmodel.document.ActivityDelegate;
@@ -105,6 +104,11 @@ public class DocumentModeAssassin {
     /** Which TabModelSelectorImpl to copy files into during migration. */
     private static final int TAB_MODEL_INDEX = 0;
 
+    public static final String OPT_OUT_STATE = "opt_out_state";

[gone, 2016/05/25 17:48:51]

Add a comment here describing how these are/were used?  I don't think some are
used anymore.

[Peter Wen, 2016/05/26 16:17:55]

Done.

+    public static final int OPT_IN_TO_DOCUMENT_MODE = 0;
+    public static final int OPT_OUT_PROMO_DISMISSED = 1;
+    public static final int OPTED_OUT_OF_DOCUMENT_MODE = 2;
+
     /** Creates and holds the Singleton. */
     private static class LazyHolder {
         private static final DocumentModeAssassin INSTANCE = new DocumentModeAssassin();
@@ -364,8 +368,7 @@ public class DocumentModeAssassin {
         // Record that the user has opted-out of document mode now that their data has been
         // safely copied to the other directory.
         Log.d(TAG, "Setting tabbed mode preference.");
-        DocumentModeManager.getInstance(getContext()).setOptedOutState(
-                DocumentModeManager.OPTED_OUT_OF_DOCUMENT_MODE);
+        setOptedOutState(OPTED_OUT_OF_DOCUMENT_MODE);
         TabSwitcherCallout.setIsTabSwitcherCalloutNecessary(getContext(), true);
 
         // Remove all the {@link DocumentActivity} tasks from Android's Recents list.  Users
@@ -545,4 +548,15 @@ public class DocumentModeAssassin {
     protected File getTabbedDataDirectory() {
         return TabPersistentStore.getOrCreateSelectorStateDirectory(TAB_MODEL_INDEX);
     }
-}
+
+    /** @return Whether the user set a preference to not use the document mode. */
+    public static boolean isOptedOutOfDocumentMode() {
+        return ContextUtils.getAppSharedPreferences().getInt(
+                OPT_OUT_STATE, OPTED_OUT_OF_DOCUMENT_MODE) == OPTED_OUT_OF_DOCUMENT_MODE;

[gone, 2016/05/25 18:26:05]

I'm really wary of this logic change.  Can you do manual testing to confirm that
users in document mode on M50 are migrated out correctly?  You'll need a local
M50 build in document mode to check.

[Peter Wen, 2016/05/26 16:17:55]

I've been trying to test the migration path this morning, but having a lot of
difficulty doing so. I tried downloading the app from go/clank-apks and building
release official stable, but the ToT version has "developer version" and doesn't
want to migrate. How do you normally test this or get a local build of M50?

+    }
+
+    /** @param state One of OPTED_OUT_OF_DOCUMENT_MODE or OPT_OUT_PROMO_DISMISSED. */
+    public static void setOptedOutState(int state) {

[gone, 2016/05/25 18:26:05]

private?

[Peter Wen, 2016/05/26 16:17:55]

Done.

+        ContextUtils.getAppSharedPreferences().edit().putInt(OPT_OUT_STATE, state).apply();
+    }
+}