Load native libraries earlier in startup

This change kicks off native library loading as early as possible in a
separate thread, to reduce startup latency. There may be a few
activities that don't actually need native libs, but the vast majority
of the time we end up loading the native lib, and this seems like a good
trade off for the perf improvements.

Pinpoint results for messageloop_start_time in mobile.startup:
Android Go:
Cold start: -11.3% https://pinpoint-dot-chromeperf.appspot.com/job/10e6fbf3520000
Warm start: -23%: https://pinpoint-dot-chromeperf.appspot.com/job/1227a4cd520000

Pixel 2:
Cold start: -0.3% https://pinpoint-dot-chromeperf.appspot.com/job/11822b23520000
Warm start: -1.7% https://pinpoint-dot-chromeperf.appspot.com/job/154a85cb520000

Bug: 1148803
Change-Id: I70256509cad47c20ec047222ba7bd0f576abe548
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2535732
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827862}

chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java

@@ -21,6 +21,7 @@ import org.chromium.base.LocaleUtils;
 import org.chromium.base.PathUtils;
 import org.chromium.base.TraceEvent;
 import org.chromium.base.annotations.MainDex;
+import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.memory.MemoryPressureMonitor;
 import org.chromium.chrome.browser.background_task_scheduler.ChromeBackgroundTaskFactory;
 import org.chromium.chrome.browser.base.MainDexApplicationImpl;
@@ -151,6 +152,17 @@ public class ChromeApplication extends SplitCompatApplication {
             }
         }
 
+        @Override
+        public void onCreate() {
+            super.onCreate();
+
+            if (SplitCompatApplication.isBrowserProcess()
+                    && CachedFeatureFlags.isEnabled(ChromeFeatureList.EARLY_LIBRARY_LOAD)) {
+                // Kick off library loading in a separate thread so it's ready when we need it.
+                new Thread(() -> LibraryLoader.getInstance().ensureMainDexInitialized()).start();
+            }
+        }
+
         private static Boolean shouldUseDebugFlags() {
             return CachedFeatureFlags.isEnabled(ChromeFeatureList.COMMAND_LINE_ON_NON_ROOTED);
         }

chrome/android/java/src/org/chromium/chrome/browser/app/flags/ChromeCachedFlags.java

@@ -57,6 +57,7 @@ public class ChromeCachedFlags {
                 ChromeFeatureList.COMMAND_LINE_ON_NON_ROOTED,
                 ChromeFeatureList.CONDITIONAL_TAB_STRIP_ANDROID,
                 ChromeFeatureList.DOWNLOADS_AUTO_RESUMPTION_NATIVE,
+                ChromeFeatureList.EARLY_LIBRARY_LOAD,
                 ChromeFeatureList.HORIZONTAL_TAB_SWITCHER_ANDROID,
                 ChromeFeatureList.IMMERSIVE_UI_MODE,
                 ChromeFeatureList.INSTANT_START,

chrome/browser/chrome_browser_field_trials.cc

@@ -28,6 +28,7 @@
 #if defined(OS_ANDROID)
 #include "chrome/browser/chrome_browser_field_trials_mobile.h"
 #include "chrome/browser/flags/android/cached_feature_flags.h"
+#include "chrome/common/chrome_features.h"
 #else
 #include "chrome/browser/chrome_browser_field_trials_desktop.h"
 #endif
@@ -111,6 +112,27 @@ void ChromeBrowserFieldTrials::RegisterSyntheticTrials() {
     ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
         kReachedCodeProfilerTrial, reached_code_profiler_group);
   }
+
+  const char* group_name;
+  bool java_feature_enabled =
+      chrome::android::IsJavaDrivenFeatureEnabled(features::kEarlyLibraryLoad);
+  bool feature_enabled =
+      base::FeatureList::IsEnabled(features::kEarlyLibraryLoad);
+  // Use the default group if cc and java feature values don't agree (can happen
+  // on first startup after feature is enabled by Finch), or the feature is not
+  // overridden by Finch.
+  if (feature_enabled != java_feature_enabled ||
+      !base::FeatureList::GetInstance()->IsFeatureOverridden(
+          features::kEarlyLibraryLoad.name)) {
+    group_name = "Default";
+  } else if (java_feature_enabled) {
+    group_name = "Enabled";
+  } else {
+    group_name = "Disabled";
+  }
+  static constexpr char kEarlyLibraryLoadTrial[] = "EarlyLibraryLoadSynthetic";
+  ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
+      kEarlyLibraryLoadTrial, group_name);
 #endif  // defined(OS_ANDROID)
 }
 

chrome/browser/flags/android/chrome_feature_list.cc

@@ -88,6 +88,7 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &embedder_support::kShowTrustedPublisherURL,
     &features::kClearOldBrowsingData,
     &features::kDownloadsLocationChange,
+    &features::kEarlyLibraryLoad,
     &features::kGenericSensorExtraClasses,
     &features::kInstallableAmbientBadgeInfoBar,
     &features::kMetricsSettingsAndroid,

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/CachedFeatureFlags.java

@@ -56,6 +56,7 @@ public class CachedFeatureFlags {
             put(ChromeFeatureList.SERVICE_MANAGER_FOR_BACKGROUND_PREFETCH, true);
             put(ChromeFeatureList.COMMAND_LINE_ON_NON_ROOTED, false);
             put(ChromeFeatureList.DOWNLOADS_AUTO_RESUMPTION_NATIVE, true);
+            put(ChromeFeatureList.EARLY_LIBRARY_LOAD, false);
             put(ChromeFeatureList.PRIORITIZE_BOOTSTRAP_TASKS, true);
             put(ChromeFeatureList.IMMERSIVE_UI_MODE, false);
             put(ChromeFeatureList.SHARE_BY_DEFAULT_IN_CCT, false);

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/ChromeFeatureList.java

@@ -292,6 +292,7 @@ public abstract class ChromeFeatureList {
     public static final String DOWNLOADS_LOCATION_CHANGE = "DownloadsLocationChange";
     public static final String DOWNLOAD_LATER = "DownloadLater";
     public static final String EDIT_PASSWORDS_IN_SETTINGS = "EditPasswordsInSettings";
+    public static final String EARLY_LIBRARY_LOAD = "EarlyLibraryLoad";
     public static final String ENHANCED_PROTECTION_PROMO_CARD = "EnhancedProtectionPromoCard";
     public static final String EPHEMERAL_TAB_USING_BOTTOM_SHEET = "EphemeralTabUsingBottomSheet";
     public static final String EXPLICIT_LANGUAGE_ASK = "ExplicitLanguageAsk";

chrome/common/chrome_features.cc

@@ -332,6 +332,12 @@ const base::Feature kDownloadsLocationChange{"DownloadsLocationChange",
                                              base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
+#if defined(OS_ANDROID)
+// Enable loading native libraries earlier in startup on Android.
+const base::Feature kEarlyLibraryLoad{"EarlyLibraryLoad",
+                                      base::FEATURE_DISABLED_BY_DEFAULT};
+#endif
+
 // Enables all registered system web apps, regardless of their respective
 // feature flags.
 const base::Feature kEnableAllSystemWebApps{"EnableAllSystemWebApps",

chrome/common/chrome_features.h

@@ -213,6 +213,11 @@ COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kDownloadsLocationChange;
 #endif
 
+#if defined(OS_ANDROID)
+COMPONENT_EXPORT(CHROME_FEATURES)
+extern const base::Feature kEarlyLibraryLoad;
+#endif
+
 COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kEnableAllSystemWebApps;