Make PlatformServiceBridge instantiate PlatformServiceBridgeImpl

PlatformServiceBridge, instead of using reflection, should load
an instance of PlatformServiceBridgeImpl that is determined by GN.
A downstream cl, which should land first, provides an alternate
implementation of PlatformServiceBridgeImpl.

Bug: 682070
Change-Id: I642603ccb4e4dd4a602803772acd343bfe6cf0dd
Reviewed-on: https://chromium-review.googlesource.com/897994
Commit-Queue: James Wallace-Lee <jamwalla@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Paul Miller <paulmiller@chromium.org>
Reviewed-by: Changwan Ryu <changwan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540752}

android_webview/BUILD.gn

@@ -941,15 +941,23 @@ java_strings_grd("strings_grd") {
 }
 
 # Separate target to allow for a dependency on GmsCore without pulling in all of
-# android_webview_java.
+# android_webview_java. It compiles the abstract class; implementations are
+# compiled separately.
 android_library("android_webview_platform_services_java") {
-  java_files =
-      [ "java/src/org/chromium/android_webview/PlatformServiceBridge.java" ]
+  java_files = [
+    "java/src/org/chromium/android_webview/PlatformServiceBridge.java",
+    "java/src/org/chromium/android_webview/PlatformServiceBridgeImpl.java",
+  ]
 
   deps = [
     "//base:base_java",
     "//third_party/android_tools:android_support_annotations_java",
   ]
+
+  # The appropriate .class file will be loaded via a dependency to a library
+  # like :platform_service_bridge_upstream_implementation_java below. We only include the
+  # .java file because other files in the target depend on it.
+  jar_excluded_patterns = [ "*/PlatformServiceBridgeImpl.class" ]
 }
 
 # This target compiles the implementation of PlatformServiceBridge for AOSP targets.
@@ -1010,6 +1018,7 @@ if (public_android_sdk) {
     android_manifest = system_webview_android_manifest
     android_manifest_dep = ":system_webview_manifest"
     deps = [
+      ":platform_service_bridge_upstream_implementation_java",
       ":system_webview_resources",
       "//android_webview/glue",
       "//android_webview/support_library:support_lib_glue_java",

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

@@ -8,17 +8,13 @@ import android.content.Context;
 import android.support.annotation.NonNull;
 
 import org.chromium.base.Callback;
-import org.chromium.base.Log;
-import org.chromium.base.StrictModeContext;
 import org.chromium.base.ThreadUtils;
 
-import java.lang.reflect.InvocationTargetException;
-
 /**
  * This class manages platform-specific services. (i.e. Google Services) The platform
  * should extend this class and use this base class to fetch their specialized version.
  */
-public class PlatformServiceBridge {
+public abstract class PlatformServiceBridge {
     private static final String TAG = "PlatformServiceBrid-";
     private static final String PLATFORM_SERVICE_BRIDGE =
             "com.android.webview.chromium.PlatformServiceBridgeGoogle";
@@ -31,27 +27,12 @@ public class PlatformServiceBridge {
     @SuppressWarnings("unused")
     public static PlatformServiceBridge getInstance() {
         synchronized (sInstanceLock) {
-            if (sInstance != null) return sInstance;
-
-            // Try to get a specialized service bridge. Starting with Android O, failed reflection
-            // may cause file reads. The reflection will go away soon: https://crbug.com/682070
-            try (StrictModeContext unused = StrictModeContext.allowDiskReads()) {
-                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());
+            if (sInstance == null) {
+                // Load an instance of PlatformServiceBridgeImpl. Because this can change
+                // depending on the GN configuration, this may not be the PlatformServiceBridgeImpl
+                // defined upstream.
+                sInstance = new PlatformServiceBridgeImpl();
             }
-
-            // Otherwise, get the generic service bridge.
-            sInstance = new PlatformServiceBridge();
             return sInstance;
         }
     }

android_webview/test/BUILD.gn

@@ -22,6 +22,7 @@ android_apk("webview_instrumentation_apk") {
     ":android_webview_apk_resources",
     "//android_webview:android_webview_java",
     "//android_webview:locale_pak_assets",
+    "//android_webview:platform_service_bridge_upstream_implementation_java",
     "//base:base_java",
     "//base:base_java_test_support",
     "//components/policy/android:policy_java_test_support",

chrome/android/BUILD.gn

@@ -1115,6 +1115,7 @@ monochrome_public_apk_tmpl("monochrome_public_apk") {
 
   deps = [
     ":monochrome_java",
+    "//android_webview:platform_service_bridge_upstream_implementation_java",
     "//base:base_java",
     "//chrome/android:app_hooks_java",
     "//chrome/android:chrome_java",