Reland "[WebLayer] Fix relro sharing in GPU and load native lib in the background"

This is a reland of f63587ac

Reason for reland: This broke on L because loadNativeLibrary returns
void and it was being cast to int. We don't actually use the return
value for anything, so just return success on L/M.

Original change's description:
> [WebLayer] Fix relro sharing in GPU and load native lib in the background
>
> WebLayer relro sharing in the browser process has likely always been
> broken in WebView compatibility mode because the ClassLoader created
> does not have a class loader namespace, see here: https://cs.android.com/android/platform/superproject/+/master:frameworks/base/native/webview/loader/loader.cpp;l=129-132;drc=master
> Unfortunately, this is difficult to fix since sharing relro in WebLayer
> when it is loaded in the same process as WebView causes crashes. This
> will be investigated more in a follow up.
>
> Relro sharing was never implemented for the WebLayer GPU process, and
> this change adds support to do that.
>
> In addition, library loading is kicked off on a separate thread much
> earlier in startup, which allows it to finish before it is needed on the
> UI thread.
>
> Pinpoint runs:
> startup.mobile: https://pinpoint-dot-chromeperf.appspot.com/job/169ab7ef520000
> -18.4% messageloop_start_time
> -3.4% navigation_commit_time
> -1.8% first_contentful_paint_time
>
> weblayer_startup: https://pinpoint-dot-chromeperf.appspot.com/job/17959d48d20000
> -6.4% weblayer_startup_wall_time
>
> system_health.memory_mobile: https://pinpoint-dot-chromeperf.appspot.com/job/16d61b37520000
> -10.0% (3.9MiB) all_processes private_dirty_size
> -29.8% (3.7Mib) gpu_process private_dirty_size
>
> Bug: 1146438
> Change-Id: I52292f0472f18397b0a900307649e6f1b54bd5c1
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2581007
> Commit-Queue: Clark DuVall <cduvall@chromium.org>
> Reviewed-by: Richard Coles <torne@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#835580}

Bug: 1146438
Change-Id: I189a6a3605174a60a5269839c6cb3ce89c18efbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2586518
Auto-Submit: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836774}

base/android/java/src/org/chromium/base/library_loader/LibraryLoader.java

@@ -425,7 +425,7 @@ public class LibraryLoader {
     }
 
     private void loadWithChromiumLinker(ApplicationInfo appInfo, String library) {
-        Linker linker = Linker.getInstance();
+        Linker linker = Linker.getInstance(appInfo);
 
         if (isInZipFile()) {
             String sourceDir = appInfo.sourceDir;

base/android/java/src/org/chromium/base/library_loader/Linker.java

@@ -5,6 +5,7 @@
 package org.chromium.base.library_loader;
 
 import android.annotation.SuppressLint;
+import android.content.pm.ApplicationInfo;
 import android.os.Bundle;
 import android.os.Parcel;
 import android.os.ParcelFileDescriptor;
@@ -202,7 +203,7 @@ public abstract class Linker {
      *
      * @return the Linker implementation instance.
      */
-    public static Linker getInstance() {
+    public static Linker getInstance(ApplicationInfo info) {
         // A non-monochrome APK (such as ChromePublic.apk) can be installed on N+ in these
         // circumstances:
         // * installing APK manually
@@ -222,8 +223,7 @@ public abstract class Linker {
             if (sSingleton == null) {
                 // With incremental install, it's important to fall back to the "normal"
                 // library loading path in order for the libraries to be found.
-                String appClass =
-                        ContextUtils.getApplicationContext().getApplicationInfo().className;
+                String appClass = info.className;
                 boolean isIncrementalInstall =
                         appClass != null && appClass.contains("incrementalinstall");
                 if (LibraryLoader.getInstance().useModernLinker() && !isIncrementalInstall) {
@@ -237,6 +237,14 @@ public abstract class Linker {
         }
     }
 
+    /**
+     * Version of getInstance() which will use the ApplicationInfo from
+     * ContextUtils.getApplicationContext().
+     */
+    public static Linker getInstance() {
+        return getInstance(ContextUtils.getApplicationContext().getApplicationInfo());
+    }
+
     /**
      * Obtain a random base load address at which to place loaded libraries.
      *

weblayer/browser/java/org/chromium/weblayer_private/ChildProcessServiceImpl.java

@@ -27,6 +27,8 @@ public final class ChildProcessServiceImpl extends IChildProcessService.Stub {
 
     @UsedByReflection("WebLayer")
     public static IBinder create(Service service, Context appContext, Context remoteContext) {
+        WebLayerImpl.setLibraryPreloader(
+                remoteContext.getPackageName(), remoteContext.getClassLoader());
         ClassLoaderContextWrapperFactory.setLightDarkResourceOverrideContext(
                 remoteContext, remoteContext);
         // Wrap the app context so that it can be used to load WebLayer implementation classes.

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -44,6 +44,7 @@ import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.NativeMethods;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.library_loader.LibraryProcessType;
+import org.chromium.base.library_loader.NativeLibraryPreloader;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.components.browser_ui.contacts_picker.ContactsPickerDialog;
 import org.chromium.components.browser_ui.photo_picker.DecoderServiceHost;
@@ -220,6 +221,13 @@ public final class WebLayerImpl extends IWebLayer.Stub {
             notifyWebViewRunningInProcess(remoteContext.getClassLoader());
         }
 
+        // Load library in the background since it may be expensive.
+        // TODO(crbug.com/1146438): Look into enabling relro sharing in browser process. It seems to
+        // crash when WebView is loaded in the same process.
+        new Thread(() -> {
+            LibraryLoader.getInstance().loadNowOverrideApplicationContext(remoteContext);
+        }).start();
+
         Context appContext = minimalInitForContext(
                 ObjectWrapper.unwrap(appContextWrapper, Context.class), remoteContext);
         PackageInfo packageInfo = WebViewFactory.getLoadedPackageInfo();
@@ -251,12 +259,6 @@ public final class WebLayerImpl extends IWebLayer.Stub {
                 /*readCommandLine=*/true);
         TraceEvent.begin("WebLayer init");
 
-        // If a remote context is not provided, the client is an older version that loads the native
-        // library on the client side.
-        if (remoteContextWrapper != null) {
-            loadNativeLibrary(packageInfo.packageName);
-        }
-
         BuildInfo.setBrowserPackageInfo(packageInfo);
         BuildInfo.setFirebaseAppId(
                 FirebaseConfig.getFirebaseAppIdForPackage(packageInfo.packageName));
@@ -278,10 +280,6 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         DeviceUtils.addDeviceSpecificUserAgentSwitch();
         ContentUriUtils.setFileProviderUtil(new FileProviderHelper());
 
-        // TODO: Validate that doing this disk IO on the main thread is necessary.
-        try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
-            LibraryLoader.getInstance().ensureInitialized();
-        }
         GmsBridge.getInstance().setSafeBrowsingHandler();
         GmsBridge.getInstance().initializeBuiltInPaymentApps();
 
@@ -322,6 +320,17 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         TraceEvent.end("WebLayer init");
     }
 
+    public static void setLibraryPreloader(String packageName, ClassLoader classLoader) {
+        if (!LibraryLoader.getInstance().isLoadedByZygote()) {
+            LibraryLoader.getInstance().setNativeLibraryPreloader(new NativeLibraryPreloader() {
+                @Override
+                public int loadLibrary(ApplicationInfo info) {
+                    return loadNativeLibrary(packageName, classLoader);
+                }
+            });
+        }
+    }
+
     @Override
     public IBrowserFragment createBrowserFragmentImpl(
             IRemoteFragmentClient fragmentClient, IObjectWrapper fragmentArgs) {
@@ -751,20 +760,21 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         }
     }
 
-    private void loadNativeLibrary(String packageName) {
+    private static int loadNativeLibrary(String packageName, ClassLoader cl) {
         // Loading the library triggers disk access.
         try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-                WebViewFactory.loadWebViewNativeLibraryFromPackage(
-                        packageName, getClass().getClassLoader());
+                return WebViewFactory.loadWebViewNativeLibraryFromPackage(packageName, cl);
             } else {
                 try {
                     Method loadNativeLibrary =
                             WebViewFactory.class.getDeclaredMethod("loadNativeLibrary");
                     loadNativeLibrary.setAccessible(true);
                     loadNativeLibrary.invoke(null);
+                    return 0; // LIBLOAD_SUCCESS
                 } catch (ReflectiveOperationException e) {
                     Log.e(TAG, "Failed to load native library.", e);
+                    return 6; // LIBLOAD_FAILED_TO_LOAD_LIBRARY
                 }
             }
         }