Extend the multidex logic to only kick in for the main browser application.

base/android/java/templates/ChromiumMultiDex.template

Index: base/android/java/templates/ChromiumMultiDex.template
diff --git a/base/android/java/templates/ChromiumMultiDex.template b/base/android/java/templates/ChromiumMultiDex.template
index 5761a454541079045caf4e26fcd5a386e1513e6f..441294c1c07d4d899598cf8674ba606aa5c50148 100644
--- a/base/android/java/templates/ChromiumMultiDex.template
+++ b/base/android/java/templates/ChromiumMultiDex.template
@@ -4,7 +4,11 @@
 
 package org.chromium.base.multidex;
 
+import android.app.ActivityManager;
+import android.app.ActivityManager.RunningAppProcessInfo;
 import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
 import android.os.Build;
 import android.os.Process;
 import android.support.multidex.MultiDex;
@@ -13,6 +17,7 @@ import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 
 import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 
 /**
  *  Performs multidex installation for non-isolated processes.
@@ -22,6 +27,12 @@ public class ChromiumMultiDex {
     private static final String TAG = "base_multidex";
 
     /**
+     * Suffix for the meta-data tag in the AndroidManifext.xml that determines whether loading
+     * secondary dexes should be skipped for a given process name.
+     */
+    private static final String IGNORE_MULTIDEX_KEY = ".ignore_multidex";
+
+    /**
      *  Installs secondary dexes if possible/necessary.
      *
      *  Isolated processes (e.g. renderer processes) can't load secondary dex files on
@@ -38,28 +49,65 @@ public class ChromiumMultiDex {
     @VisibleForTesting
 #if defined(MULTIDEX_CONFIGURATION_Debug)
     public static void install(Context context) {
+        // TODO(jbudorick): Back out this version check once support for K & below works.
+        // http://crbug.com/512357
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP
+                && !shouldInstallMultiDex(context)) {
+            Log.i(TAG, "Skipping multidex installation: not needed for process.");
+        } else {
+            MultiDex.install(context);
+            Log.i(TAG, "Completed multidex installation.");
+        }
+    }
+
+    private static String getProcessName(Context context) {
         try {
-            // TODO(jbudorick): Back out this version check once support for K & below works.
-            // http://crbug.com/512357
-            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP && processIsIsolated()) {
-                Log.i(TAG, "Skipping multidex installation: inside isolated process.");
-            } else {
-                MultiDex.install(context);
-                Log.i(TAG, "Completed multidex installation.");
+            String currentProcessName = null;
+            int pid = android.os.Process.myPid();
+
+            ActivityManager manager =
+                    (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
+            for (RunningAppProcessInfo processInfo : manager.getRunningAppProcesses()) {
+                if (processInfo.pid == pid) {
+                    currentProcessName = processInfo.processName;
+                    break;
+                }
             }
-        } catch (NoSuchMethodException e) {
-            Log.wtf(TAG, "Failed multidex installation", e);
-        } catch (IllegalAccessException e) {
-            Log.wtf(TAG, "Failed multidex installation", e);
-        } catch (InvocationTargetException e) {
-            Log.wtf(TAG, "Failed multidex installation", e);
+
+            return currentProcessName;
+        } catch (SecurityException ex) {
+            return null;
         }
     }
 
-    // Calls Process.isIsolated, a private Android API.
-    private static boolean processIsIsolated()
-            throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
-        return (boolean) Process.class.getMethod("isIsolated").invoke(null);
+    // Determines whether MultiDex should be installed for the current process.  Isolated
+    // Processes should skip MultiDex as they can not actually access the files on disk.
+    // Privileged processes need ot have all of their dependencies in the MainDex for
+    // performance reasons. 
+    private static boolean shouldInstallMultiDex(Context context) {
+        try {
+            Method isIsolatedMethod =
+                    android.os.Process.class.getMethod("isIsolated");
+            Object retVal = isIsolatedMethod.invoke(null);
+            if (retVal != null && retVal instanceof Boolean && ((Boolean) retVal)) {
+                return false;
+            }
+        } catch (IllegalAccessException | IllegalArgumentException
+                | InvocationTargetException | NoSuchMethodException e) {
+            // Ignore and fall back to checking the app processes.
+        }
+
+        String currentProcessName = getProcessName(context);
+        if (currentProcessName == null) return true;
+        
+        PackageManager packageManager = context.getPackageManager();
+        try {
+            ApplicationInfo appInfo = packageManager.getApplicationInfo(context.getPackageName(),
+                    PackageManager.GET_META_DATA);
+            return !appInfo.metaData.getBoolean(currentProcessName + IGNORE_MULTIDEX_KEY, false);
+        } catch (PackageManager.NameNotFoundException e) {
+            return true;
+        }
     }
 #else
     public static void install(Context context) {