WebView: Refactor PlatformServiceBridge.getInstance()

android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java

Index: android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
diff --git a/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java b/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
index 7957e96e4f5a496dfce8b0cd7d105bdc0858867a..1356aa428068ed33a4b642a25bfa354e68ce5b38 100644
--- a/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
+++ b/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
@@ -4,10 +4,8 @@
 
 package org.chromium.android_webview;
 
-import android.content.Context;
 import android.webkit.ValueCallback;
 
-import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 
@@ -22,53 +20,44 @@ public class PlatformServiceBridge {
     private static final String PLATFORM_SERVICE_BRIDGE =
             "com.android.webview.chromium.PlatformServiceBridgeGoogle";
 
-    // Only written by getOrCreateInstance on the UI thread (aside from injectInstance, for
-    // testing), but read by getInstance on arbitrary threads.
-    private static volatile PlatformServiceBridge sInstance;
+    private static PlatformServiceBridge sInstance;
+    private static final Object sInstanceLock = new Object();
 
     protected PlatformServiceBridge() {}
 
-    public static PlatformServiceBridge getOrCreateInstance() {
-        // Just to avoid race conditions on sInstance - nothing special about the UI thread.
-        ThreadUtils.assertOnUiThread();
-
-        if (sInstance != null) return sInstance;
-
-        // Try to get a specialized service bridge.
-        try {
-            Class<?> cls = Class.forName(PLATFORM_SERVICE_BRIDGE);
-            sInstance = (PlatformServiceBridge) cls.getDeclaredConstructor(Context.class)
-                                .newInstance(ContextUtils.getApplicationContext());
+    public static PlatformServiceBridge getInstance() {
+        synchronized (sInstanceLock) {
+            if (sInstance != null) return sInstance;
+
+            // Try to get a specialized service bridge.
+            try {
+                Class<?> cls = Class.forName(PLATFORM_SERVICE_BRIDGE);
+                sInstance = (PlatformServiceBridge) cls.getDeclaredConstructor().newInstance();
+                return sInstance;
+            } catch (ClassNotFoundException e) {
+                // This is not an error; it just means this device doesn't have specialized
+                // services.
+            } catch (IllegalAccessException | IllegalArgumentException | InstantiationException
+                    | NoSuchMethodException e) {
+                Log.e(TAG, "Failed to get " + PLATFORM_SERVICE_BRIDGE + ": " + e);
+            } catch (InvocationTargetException e) {
+                Log.e(TAG, "Failed invocation to get " + PLATFORM_SERVICE_BRIDGE + ": ",
+                        e.getCause());
+            }
+
+            // Otherwise, get the generic service bridge.
+            sInstance = new PlatformServiceBridge();
             return sInstance;
-        } catch (ClassNotFoundException e) {
-            // This is not an error; it just means this device doesn't have specialized
-            // services.
-        } catch (IllegalAccessException | IllegalArgumentException | InstantiationException
-                | NoSuchMethodException e) {
-            Log.e(TAG, "Failed to get " + PLATFORM_SERVICE_BRIDGE + ": " + e);
-        } catch (InvocationTargetException e) {
-            Log.e(TAG, "Failed invocation to get " + PLATFORM_SERVICE_BRIDGE + ":", e.getCause());
         }
-
-        // Otherwise, get the generic service bridge.
-        sInstance = new PlatformServiceBridge();
-
-        return sInstance;
-    }
-
-    public static PlatformServiceBridge getInstance() {
-        if (sInstance == null) throw new IllegalStateException("PlatformServiceBridge not created");
-        return sInstance;
     }
 
     // Provide a mocked PlatformServiceBridge for testing.
     public static void injectInstance(PlatformServiceBridge testBridge) {
-        sInstance = testBridge;
-    }
-
-    // TODO(paulmiller): Remove after changing downstream users.
-    public static PlatformServiceBridge getInstance(Context context) {
-        return getInstance();
+        // Although reference assignments are atomic, we still wouldn't want to assign it in the
+        // middle of getInstance().
+        synchronized (sInstanceLock) {
+            sInstance = testBridge;
+        }
     }
 
     // Can WebView use Google Play Services (a.k.a. GMS)?