Make sure chrome split preload has finished before creating activities

I saw some of the class loader mismatch crashes came back after adding
preloading. This will hopefully fix those crashes.

Bug: 1146745
Change-Id: I9e9364ba6d0a69bb38267905461961c018e73133
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2606193Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839632}

chrome/android/java/src/org/chromium/chrome/browser/base/SplitChromeApplication.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.base;
 
 import static org.chromium.chrome.browser.base.SplitCompatUtils.CHROME_SPLIT_NAME;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.Context;
 import android.content.ContextWrapper;
@@ -42,8 +43,11 @@ import java.lang.reflect.Field;
  */
 public class SplitChromeApplication extends SplitCompatApplication {
     private static final String TAG = "SplitChromeApp";
+
+    @SuppressLint("StaticFieldLeak")
+    private static SplitPreloader sSplitPreloader;
+
     private String mChromeApplicationClassName;
-    private SplitPreloader mSplitPreloader;
 
     public SplitChromeApplication() {
         this(SplitCompatUtils.getIdentifierName(
@@ -56,9 +60,7 @@ public class SplitChromeApplication extends SplitCompatApplication {
 
     @Override
     public void onCreate() {
-        if (mSplitPreloader != null) {
-            mSplitPreloader.wait(CHROME_SPLIT_NAME);
-        }
+        finishPreload(CHROME_SPLIT_NAME);
         super.onCreate();
     }
 
@@ -81,11 +83,9 @@ public class SplitChromeApplication extends SplitCompatApplication {
     @Override
     public Context createContextForSplit(String name) throws PackageManager.NameNotFoundException {
         try (TraceEvent te = TraceEvent.scoped("SplitChromeApplication.createContextForSplit")) {
-            if (mSplitPreloader != null) {
-                // Wait for any splits that are preloading so we don't have a race to update the
-                // class loader cache (b/172602571).
-                mSplitPreloader.wait(name);
-            }
+            // Wait for any splits that are preloading so we don't have a race to update the
+            // class loader cache (b/172602571).
+            finishPreload(name);
             long startTime = SystemClock.uptimeMillis();
             Context context = super.createContextForSplit(name);
             RecordHistogram.recordTimesHistogram("Android.IsolatedSplits.ContextCreateTime." + name,
@@ -99,13 +99,13 @@ public class SplitChromeApplication extends SplitCompatApplication {
         // The chrome split has a large amount of code, which can slow down startup. Loading
         // this in the background allows us to do this in parallel with startup tasks which do
         // not depend on code in the chrome split.
-        mSplitPreloader = new SplitPreloader(context);
+        sSplitPreloader = new SplitPreloader(context);
         // If the chrome module is not enabled or isolated splits are not supported (e.g. in Android
         // N), the onComplete function will run immediately so it must handle the case where the
         // base context of the application has not been set yet.
-        mSplitPreloader.preload(CHROME_SPLIT_NAME, (chromeContext) -> {
+        sSplitPreloader.preload(CHROME_SPLIT_NAME, (chromeContext) -> {
             // When installed, the vr module is always loaded on startup, so preload here.
-            mSplitPreloader.preload("vr", null);
+            sSplitPreloader.preload("vr", null);
             // If the chrome module is not enabled or isolated splits are not supported,
             // chromeContext will have the same ClassLoader as the base context, so no need to
             // replace the ClassLoaders here.
@@ -120,6 +120,12 @@ public class SplitChromeApplication extends SplitCompatApplication {
         return new Impl();
     }
 
+    /* package */ static void finishPreload(String name) {
+        if (sSplitPreloader != null) {
+            sSplitPreloader.wait(name);
+        }
+    }
+
     /**
      * Fixes Activity ClassLoader if necessary. Isolated splits can cause a ClassLoader mismatch
      * between the Application and Activity ClassLoaders. We have a workaround in

chrome/android/java/src/org/chromium/chrome/browser/base/SplitCompatAppComponentFactory.java

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.base;
 
+import static org.chromium.chrome.browser.base.SplitCompatUtils.CHROME_SPLIT_NAME;
+
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.AppComponentFactory;
@@ -32,6 +34,9 @@ public class SplitCompatAppComponentFactory extends AppComponentFactory {
     @Override
     public Activity instantiateActivity(ClassLoader cl, String className, Intent intent)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
+        // Activities will not call createContextForSplit() which will normally ensure the preload
+        // is finished, so we have to manually ensure that here.
+        SplitChromeApplication.finishPreload(CHROME_SPLIT_NAME);
         return super.instantiateActivity(getComponentClassLoader(cl, className), className, intent);
     }