[WebView] initial webview-side implementation of safebrowsing

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 b41d09121b8dfaabb5185221137e20e13bf72594..3f906a92b23f8a32e33da48e231f68bbab223b70 100644
--- a/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
+++ b/android_webview/java/src/org/chromium/android_webview/PlatformServiceBridge.java
@@ -21,34 +21,38 @@ public class PlatformServiceBridge {
     private static final String PLATFORM_SERVICE_BRIDGE =
             "com.android.webview.chromium.PlatformServiceBridgeGoogle";
 
+    private static final Object sInstanceLock = new Object();
     private static PlatformServiceBridge sInstance;
 
     protected PlatformServiceBridge() {}
 
     public static PlatformServiceBridge getInstance(Context appContext) {
-        ThreadUtils.assertOnUiThread(); // Avoid race conditions on sInstance.
+        // TODO(timvolodine): consider removing the lock, crbug.com/681805.
+        synchronized (sInstanceLock) {
+            if (sInstance != null) {
+                return sInstance;
+            }
 
-        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(appContext);
+                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());
+            }
 
-        // Try to get a specialized service bridge.
-        try {
-            Class<?> cls = Class.forName(PLATFORM_SERVICE_BRIDGE);
-            sInstance = (PlatformServiceBridge) cls.getDeclaredConstructor(Context.class)
-                    .newInstance(appContext);
-            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();
         }
-
-        // Otherwise, get the generic service bridge.
-        sInstance = new PlatformServiceBridge();
         return sInstance;
     }