Defer deferred startup if native isn't loaded

There's a race condition that's causing a tab to finish
loading before onStartWithNative has successfully run.
It's not entirely clear where the race condition lies
because the startup pathway is complicated, so prevent
deferred startup from running until native has loaded.

BUG=711708

Review-Url: https://codereview.chromium.org/2855043002
Cr-Commit-Position: refs/heads/master@{#469013}

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

@@ -226,7 +226,12 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
 
     protected IntentHandler mIntentHandler;
 
+    /** Set if {@link #postDeferredStartupIfNeeded()} is called before native has loaded. */
+    private boolean mDeferredStartupQueued;
+
+    /** Whether or not {@link #postDeferredStartupIfNeeded()} has already successfully run. */
     private boolean mDeferredStartupPosted;
+
     private boolean mTabModelsInitialized;
     private boolean mNativeInitialized;
     private boolean mRemoveWindowBackgroundDone;
@@ -764,6 +769,8 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
 
     @Override
     public void onStartWithNative() {
+        assert mNativeInitialized : "onStartWithNative was called before native was initialized.";
+
         super.onStartWithNative();
         UpdateMenuItemHelper.getInstance().onStart();
         ChromeActivitySessionTracker.getInstance().onStartWithNative();
@@ -779,7 +786,7 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
         // #onPageLoadFinished() and #onCrash(). If we are not actively loading a tab (e.g.
         // in Android N multi-instance, which is created by re-parenting an existing tab),
         // ensure onDeferredStartup() gets called by calling postDeferredStartupIfNeeded() here.
-        if (getActivityTab() == null || !getActivityTab().isLoading()) {
+        if (mDeferredStartupQueued || getActivityTab() == null || !getActivityTab().isLoading()) {
             postDeferredStartupIfNeeded();
         }
     }
@@ -2010,6 +2017,13 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
     }
 
     protected final void postDeferredStartupIfNeeded() {
+        if (!mNativeInitialized) {
+            // Native hasn't loaded yet.  Queue it up for later.
+            mDeferredStartupQueued = true;
+            return;
+        }
+        mDeferredStartupQueued = false;
+
         if (!mDeferredStartupPosted) {
             mDeferredStartupPosted = true;
             RecordHistogram.recordLongTimesHistogram(