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

base/android/java/templates/ChromiumMultiDex.template

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.base.multidex;
 
+import android.app.ActivityManager;
+import android.app.ActivityManager.RunningAppProcessInfo;
 import android.content.Context;
 import android.os.Build;
 import android.os.Process;
 import android.support.multidex.MultiDex;
 
 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.
  */
 public class ChromiumMultiDex {
 
     private static final String TAG = "base_multidex";
 
     /**
      *  Installs secondary dexes if possible/necessary.
      *
      *  Isolated processes (e.g. renderer processes) can't load secondary dex files on
      *  K and below, so we don't even try in that case.
      *
      *  In release builds, this is a no-op because:
      *    - multidex isn't necessary in release builds because we run proguard there and
      *      thus aren't threatening to hit the dex limit; and
      *    - calling MultiDex.install, even in the absence of secondary dexes, causes a
      *      significant regression in start-up time (crbug.com/525695).
      *
      *  @param context The application context.
      */
     @VisibleForTesting
 #if defined(MULTIDEX_CONFIGURATION_Debug)
     public static void install(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.");
-            }
-        } 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);
+        // 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
+                && !isBrowserApplicationProcess(context)) {
+            Log.i(TAG, "Skipping multidex installation: inside non browser process.");
+        } else {
+            MultiDex.install(context);
+            Log.i(TAG, "Completed multidex installation.");
         }
     }
 
-    // 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 the current context is for the main browser application.
+    private static boolean isBrowserApplicationProcess(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.
+        }
+
+        try {

[nyquist, 2015/11/25 00:12:52]

Nit: Could you extract most of this block out to a private static
getCurrentProcessName() (except the return check...)?

+            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;
+                }
+            }
+
+            return currentProcessName != null && !currentProcessName.contains(":");

[nyquist, 2015/11/25 00:12:52]

Could you add a comment explaining the significance of a colon being part of the
process name? 

+        } catch (SecurityException ex) {
+            return false;
+        }
     }
 #else
     public static void install(Context context) {
     }
 #endif
 
 }