Android: Make Linker.java optimized out when use_chromium_linker=false

Two fixes:
1) Move static getters to a separate LibraryLoaderConfig.java
   * Required because of the non-trivial class initializer in
     LibraryLoader preventing inlining.
2) Change JNI proguard rules to not -keep natives when the linker
   is not used.

TBR=agrieve  # Renames

Change-Id: I0f4a40af6168cbe7243f462c24d230d277e642ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1703155
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Sam Maier <smaier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692146}

android_webview/apk/java/proguard.flags

@@ -39,10 +39,6 @@
 -keep class com.android.webview.chromium.DrawGLFunctor
 -keep class com.android.webview.chromium.GraphicsUtils
 
-# Linker dynamically casts to $TestRunner when running tests. We don't run these
-# tests in WebView.
--dontnote org.chromium.base.library_loader.Linker$TestRunner
-
 # Don't note about the API 21 compatibility code which references various
 # hidden APIs via reflection.
 -dontnote com.android.webview.chromium.WebViewDelegateFactory$Api21CompatibilityDelegate

base/BUILD.gn

@@ -3258,6 +3258,7 @@ if (is_android) {
       "android/java/src/org/chromium/base/compat/ApiHelperForP.java",
       "android/java/src/org/chromium/base/library_loader/LegacyLinker.java",
       "android/java/src/org/chromium/base/library_loader/LibraryLoader.java",
+      "android/java/src/org/chromium/base/library_loader/LibraryLoaderConfig.java",
       "android/java/src/org/chromium/base/library_loader/LibraryPrefetcher.java",
       "android/java/src/org/chromium/base/library_loader/Linker.java",
       "android/java/src/org/chromium/base/library_loader/LoaderErrors.java",

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

@@ -191,7 +191,7 @@ public class LibraryLoader {
      */
     public void preloadNowOverrideApplicationContext(Context appContext) {
         synchronized (mLock) {
-            if (useChromiumLinker()) return;
+            if (LibraryLoaderConfig.useChromiumLinker()) return;
             preloadAlreadyLocked(appContext.getApplicationInfo());
         }
     }
@@ -199,7 +199,7 @@ public class LibraryLoader {
     private void preloadAlreadyLocked(ApplicationInfo appInfo) {
         try (TraceEvent te = TraceEvent.scoped("LibraryLoader.preloadAlreadyLocked")) {
             // Preloader uses system linker, we shouldn't preload if Chromium linker is used.
-            assert !useChromiumLinker();
+            assert !LibraryLoaderConfig.useChromiumLinker();
             if (mLibraryPreloader != null && !mLibraryPreloaderCalled) {
                 mLibraryPreloader.loadLibrary(appInfo);
                 mLibraryPreloaderCalled = true;
@@ -340,7 +340,7 @@ public class LibraryLoader {
 
             long startTime = SystemClock.uptimeMillis();
 
-            if (useChromiumLinker() && !inZygote) {
+            if (LibraryLoaderConfig.useChromiumLinker() && !inZygote) {
                 Linker linker = Linker.getInstance();
 
                 // See base/android/linker/config.gni, the chromium linker is only enabled when we
@@ -559,7 +559,7 @@ public class LibraryLoader {
     // Called after all native initializations are complete.
     public void onBrowserNativeInitializationComplete() {
         synchronized (mLock) {
-            if (useChromiumLinker()) {
+            if (LibraryLoaderConfig.useChromiumLinker()) {
                 RecordHistogram.recordTimesHistogram(
                         "ChromiumAndroidLinker.BrowserLoadTime", mLibraryLoadTimeMs);
             }
@@ -572,21 +572,12 @@ public class LibraryLoader {
     // RecordChromiumAndroidLinkerRendererHistogram() will record it correctly.
     public void registerRendererProcessHistogram() {
         synchronized (mLock) {
-            if (useChromiumLinker()) {
+            if (LibraryLoaderConfig.useChromiumLinker()) {
                 LibraryLoaderJni.get().recordRendererLibraryLoadTime(mLibraryLoadTimeMs);
             }
         }
     }
 
-    /**
-     * Call this method to determine if this chromium project must
-     * use this linker. If not, System.loadLibrary() should be used to load
-     * libraries instead.
-     */
-    public static boolean useChromiumLinker() {
-        return NativeLibraries.sUseLinker;
-    }
-
     /**
      * Override the library loader (normally with a mock) for testing.
      * @param loader the mock library loader.

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

+// Copyright 2014 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.library_loader;
+
+/**
+ * Build-time configuration of LibraryLoader.
+ * These are in a separate class from LibraryLoader to ensure that they are inlined.
+ */
+public class LibraryLoaderConfig {
+    private LibraryLoaderConfig() {}
+
+    /**
+     * Check that native library linker tests are enabled.
+     * If not enabled, calls to testing functions will fail with an assertion
+     * error.
+     *
+     * @return true if native library linker tests are enabled.
+     */
+    public static boolean areTestsEnabled() {
+        return NativeLibraries.sEnableLinkerTests;
+    }
+
+    /**
+     * Call this method to determine if this chromium project must
+     * use this linker. If not, System.loadLibrary() should be used to load
+     * libraries instead.
+     */
+    public static boolean useChromiumLinker() {
+        return NativeLibraries.sUseLinker;
+    }
+}

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

@@ -600,16 +600,6 @@ public abstract class Linker {
     }
 
     /* ---------------------- Testing support methods. ---------------------- */
-    /**
-     * Check that native library linker tests are enabled.
-     * If not enabled, calls to testing functions will fail with an assertion
-     * error.
-     *
-     * @return true if native library linker tests are enabled.
-     */
-    public static boolean areTestsEnabled() {
-        return NativeLibraries.sEnableLinkerTests;
-    }
 
     /**
      * Get Linker implementation type.

base/android/proguard/chromium_code.flags

@@ -38,7 +38,7 @@
 -keepclasseswithmembers class ** {
   @org.chromium.base.annotations.UsedByReflection <fields>;
 }
--keepclasseswithmembers,includedescriptorclasses class ** {
+-keepclasseswithmembers,includedescriptorclasses class !org.chromium.base.library_loader.**,** {
   native <methods>;
 }
 

base/android/proguard/chromium_linker.flags

+# Copyright 2019 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.
+
+-keepclasseswithmembers,includedescriptorclasses class org.chromium.base.library_loader.** {
+  native <methods>;
+}

base/android/proguard/no_chromium_linker.flags

+# Copyright 2019 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.
+
+# All references to Linker.getInstance() should be guarded by:
+# LibraryLoaderConfig.useCrazyLinker().
+-checkdiscard class org.chromium.base.library_loader.Linker {
+  *;
+}

build/config/android/rules.gni

@@ -2813,6 +2813,13 @@ if (enable_java_templates) {
         if (defined(invoker.proguard_configs)) {
           proguard_configs += invoker.proguard_configs
         }
+        if (_use_chromium_linker) {
+          proguard_configs +=
+              [ "//base/android/proguard/chromium_linker.flags" ]
+        } else {
+          proguard_configs +=
+              [ "//base/android/proguard/no_chromium_linker.flags" ]
+        }
         if (_enable_main_dex_list) {
           proguard_configs += [ "//build/android/multidex.flags" ]
         }

chrome/android/chrome_public_apk_tmpl.gni

@@ -241,6 +241,20 @@ template("chrome_public_common_apk_or_module_tmpl") {
       srcjar_deps = [ "//components/module_installer/android:module_installer_apk_build_config" ]
     }
 
+    if (!defined(use_chromium_linker)) {
+      use_chromium_linker = chromium_linker_supported
+    }
+    if (use_chromium_linker) {
+      if (!defined(load_library_from_apk)) {
+        # Whether native libraries should be loaded from within the apk.
+        # Only attempt loading the library from the APK for 64 bit devices
+        # until the number of 32 bit devices which don't support this
+        # approach falls to a minimal level -  http://crbug.com/390618.
+        load_library_from_apk = chromium_linker_supported &&
+                                (current_cpu == "arm64" || current_cpu == "x64")
+      }
+    }
+
     if (!is_java_debug) {
       proguard_enabled = true
       if (!defined(proguard_configs)) {
@@ -260,20 +274,6 @@ template("chrome_public_common_apk_or_module_tmpl") {
       }
     }
 
-    if (!defined(use_chromium_linker)) {
-      use_chromium_linker = chromium_linker_supported
-    }
-
-    if (use_chromium_linker) {
-      if (!defined(load_library_from_apk)) {
-        # Whether native libraries should be loaded from within the apk.
-        # Only attempt loading the library from the APK for 64 bit devices
-        # until the number of 32 bit devices which don't support this
-        # approach falls to a minimal level -  http://crbug.com/390618.
-        load_library_from_apk = chromium_linker_supported &&
-                                (current_cpu == "arm64" || current_cpu == "x64")
-      }
-    }
     if (_target_type == "android_apk") {
       command_line_flags_file = "chrome-command-line"
     } else {

chrome/android/java/monochrome_public_bundle.proguard_flags.expected

@@ -42,10 +42,6 @@
 -keep class com.android.webview.chromium.DrawGLFunctor
 -keep class com.android.webview.chromium.GraphicsUtils
 
-# Linker dynamically casts to $TestRunner when running tests. We don't run these
-# tests in WebView.
--dontnote org.chromium.base.library_loader.Linker$TestRunner
-
 # Don't note about the API 21 compatibility code which references various
 # hidden APIs via reflection.
 -dontnote com.android.webview.chromium.WebViewDelegateFactory$Api21CompatibilityDelegate
@@ -211,7 +207,7 @@
 -keepclasseswithmembers class ** {
   @org.chromium.base.annotations.UsedByReflection <fields>;
 }
--keepclasseswithmembers,includedescriptorclasses class ** {
+-keepclasseswithmembers,includedescriptorclasses class !org.chromium.base.library_loader.**,** {
   native <methods>;
 }
 
@@ -273,6 +269,19 @@
 -renamesourcefileattribute PG
 -repackageclasses ''
 
+################################################################################
+# ../../base/android/proguard/no_chromium_linker.flags
+################################################################################
+# Copyright 2019 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.
+
+# All references to Linker.getInstance() should be guarded by:
+# LibraryLoaderConfig.useCrazyLinker().
+-checkdiscard class org.chromium.base.library_loader.Linker {
+  *;
+}
+
 ################################################################################
 # ../../build/android/buildhooks/proguard/build_hooks_android_impl.flags
 ################################################################################

chrome/android/javatests/src/org/chromium/chrome/browser/metrics/StartupLoadingMetricsTest.java

@@ -19,7 +19,7 @@ import org.junit.runner.RunWith;
 
 import org.chromium.base.Log;
 import org.chromium.base.compat.ApiHelperForM;
-import org.chromium.base.library_loader.LibraryLoader;
+import org.chromium.base.library_loader.LibraryLoaderConfig;
 import org.chromium.base.library_loader.LoadStatusRecorder.LoadLibraryStatus;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.test.util.CommandLineFlags;
@@ -159,7 +159,7 @@ public class StartupLoadingMetricsTest {
         assertHistogramsRecorded(1, TABBED_SUFFIX);
 
         // LibraryLoader checks.
-        if (!LibraryLoader.useChromiumLinker()) {
+        if (!LibraryLoaderConfig.useChromiumLinker()) {
             Log.w(TAG, "Skipping test because not using ChromiumLinker.");
             return;
         }

content/public/android/java/src/org/chromium/content/app/ContentChildProcessServiceDelegate.java

@@ -20,6 +20,7 @@ import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.MainDex;
 import org.chromium.base.annotations.NativeMethods;
 import org.chromium.base.library_loader.LibraryLoader;
+import org.chromium.base.library_loader.LibraryLoaderConfig;
 import org.chromium.base.library_loader.Linker;
 import org.chromium.base.library_loader.ProcessInitException;
 import org.chromium.base.memory.MemoryPressureUma;
@@ -82,7 +83,8 @@ public class ContentChildProcessServiceDelegate implements ChildProcessServiceDe
         mCpuFeatures = connectionBundle.getLong(ContentChildProcessConstants.EXTRA_CPU_FEATURES);
         assert mCpuCount > 0;
 
-        if (LibraryLoader.useChromiumLinker() && !LibraryLoader.getInstance().isLoadedByZygote()) {
+        if (LibraryLoaderConfig.useChromiumLinker()
+                && !LibraryLoader.getInstance().isLoadedByZygote()) {
             Bundle sharedRelros = connectionBundle.getBundle(Linker.EXTRA_LINKER_SHARED_RELROS);
             if (sharedRelros != null) getLinker().provideSharedRelros(sharedRelros);
         }
@@ -106,7 +108,7 @@ public class ContentChildProcessServiceDelegate implements ChildProcessServiceDe
 
         Linker linker = null;
         boolean requestedSharedRelro = false;
-        if (LibraryLoader.useChromiumLinker()) {
+        if (LibraryLoaderConfig.useChromiumLinker()) {
             assert mLinkerParams != null;
             linker = getLinker();
             if (mLinkerParams.mWaitForSharedRelro) {
@@ -184,7 +186,7 @@ public class ContentChildProcessServiceDelegate implements ChildProcessServiceDe
 
     // Return a Linker instance. If testing, the Linker needs special setup.
     private Linker getLinker() {
-        if (Linker.areTestsEnabled()) {
+        if (LibraryLoaderConfig.areTestsEnabled()) {
             // For testing, set the Linker implementation and the test runner
             // class name to match those used by the parent.
             assert mLinkerParams != null;

content/public/android/java/src/org/chromium/content/browser/ChildProcessLauncherHelperImpl.java

@@ -24,7 +24,7 @@ import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 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.LibraryLoaderConfig;
 import org.chromium.base.library_loader.Linker;
 import org.chromium.base.process_launcher.ChildConnectionAllocator;
 import org.chromium.base.process_launcher.ChildProcessConnection;
@@ -133,7 +133,7 @@ public final class ChildProcessLauncherHelperImpl {
                             ContentChildProcessConstants.EXTRA_CPU_COUNT, CpuFeatures.getCount());
                     connectionBundle.putLong(
                             ContentChildProcessConstants.EXTRA_CPU_FEATURES, CpuFeatures.getMask());
-                    if (LibraryLoader.useChromiumLinker()) {
+                    if (LibraryLoaderConfig.useChromiumLinker()) {
                         connectionBundle.putBundle(Linker.EXTRA_LINKER_SHARED_RELROS,
                                 Linker.getInstance().getSharedRelros());
                     }
@@ -594,7 +594,7 @@ public final class ChildProcessLauncherHelperImpl {
     private static void initLinker() {
         assert LauncherThread.runningOnLauncherThread();
         if (sLinkerInitialized) return;
-        if (LibraryLoader.useChromiumLinker()) {
+        if (LibraryLoaderConfig.useChromiumLinker()) {
             sLinkerLoadAddress = Linker.getInstance().getBaseLoadAddress();
             if (sLinkerLoadAddress == 0) {
                 Log.i(TAG, "Shared RELRO support disabled!");
@@ -612,7 +612,7 @@ public final class ChildProcessLauncherHelperImpl {
 
         // Always wait for the shared RELROs in service processes.
         final boolean waitForSharedRelros = true;
-        if (Linker.areTestsEnabled()) {
+        if (LibraryLoaderConfig.areTestsEnabled()) {
             Linker linker = Linker.getInstance();
             return new ChromiumLinkerParams(sLinkerLoadAddress, waitForSharedRelros,
                     linker.getTestRunnerClassNameForTesting(),