Prepare to call GMS APIs from WebView

android_webview/java/src/org/chromium/android_webview/AwMetricsServiceClient.java

 // Copyright 2015 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.android_webview;
 
 import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.webkit.ValueCallback;
 
 import org.chromium.base.Log;
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 /**
- * Java twin of the homonymous C++ class. The Java side is only responsible for
- * switching metrics on and off. Since the setting is a platform feature, it
- * must be obtained through PlatformServiceBridge.
+ * Determines whether metrics should be enabled.
+ *
+ * This requires the following steps:
+ * 1) Check if the app has opted out.
+ * 2) Check the platform's metrics consent setting.
+ * 3) Wait for the native AwMetricsServiceClient to call nativeInitialized.
+ * 4) If enabled, inform the native AwMetricsServiceClient via nativeSetMetricsEnabled.

[sgurun-gerrit only, 2017/01/13 07:12:15]

I think because you start it from Java (AwContents), you need to deal with an
unnecessary extra state. Is there a reason starting the query from Native does
not work?

+ *
+ * Steps 1 and 2 are started on the Java side by calling queryMetricsSetting. This happens in
+ * parallel with native AwMetricsServiceClient initialization. Either nativeInitialized happens
+ * before onReceiveValue comes back with the platform setting, in which case we should set
+ * sIsClientReady and wait for onReceiveValue, or onReceiveValue happens before nativeInitialized,
+ * in which case we should record the setting in sShouldEnable and wait for nativeInitialized.
+ * Whichever fires last should call nativeSetMetricsEnabled.
  */
 @JNINamespace("android_webview")
 public class AwMetricsServiceClient {
     private static final String TAG = "AwMetricsServiceCli-";
 
     // Individual apps can use this meta-data tag in their manifest to opt out of metrics
     // reporting. See https://developer.android.com/reference/android/webkit/WebView.html
     private static final String OPT_OUT_META_DATA_STR = "android.webkit.WebView.MetricsOptOut";
 
-    private static boolean isAppOptedOut(Context applicationContext) {
+    private static boolean sIsClientReady; // Is the native AwMetricsServiceClient initialized?
+    private static boolean sShouldEnable; // Have steps 1 and 2 passed?
+
+    private static boolean isAppOptedOut(Context appContext) {
         try {
-            ApplicationInfo info = applicationContext.getPackageManager().getApplicationInfo(
-                    applicationContext.getPackageName(), PackageManager.GET_META_DATA);
+            ApplicationInfo info = appContext.getPackageManager().getApplicationInfo(
+                    appContext.getPackageName(), PackageManager.GET_META_DATA);
             if (info.metaData == null) {
                 // null means no such tag was found.
                 return false;
             }
             // getBoolean returns false if the key is not found, which is what we want.
             return info.metaData.getBoolean(OPT_OUT_META_DATA_STR);
         } catch (PackageManager.NameNotFoundException e) {
             // This should never happen.
             Log.e(TAG, "App could not find itself by package name!");
             // The conservative thing is to assume the app HAS opted out.
             return true;
         }
     }
 
-    public AwMetricsServiceClient(Context applicationContext) {
-        if (isAppOptedOut(applicationContext)) {
+    public static void queryMetricsSetting(Context appContext) {
+        ThreadUtils.assertOnUiThread();
+
+        // Metrics defaults to off, so only call nativeSetMetricsEnabled if it's true.
+        if (isAppOptedOut(appContext)) {
             return;
         }
 
         // Check if the user has consented.
-        PlatformServiceBridge.getInstance(applicationContext)
-                .setMetricsSettingListener(new ValueCallback<Boolean>() {
+        PlatformServiceBridge.getInstance(appContext)
+                .queryMetricsSetting(new ValueCallback<Boolean>() {
                     public void onReceiveValue(Boolean enabled) {
-                        nativeSetMetricsEnabled(enabled);
+                        ThreadUtils.assertOnUiThread();
+                        if (enabled) {
+                            sShouldEnable = true;
+                            if (sIsClientReady) {
+                                nativeSetMetricsEnabled(true);
+                            }
+                        }
                     }
                 });
     }
 
+    @CalledByNative
+    public static void nativeInitialized() {
+        ThreadUtils.assertOnUiThread();
+        sIsClientReady = true;
+        if (sShouldEnable) {
+            nativeSetMetricsEnabled(true);
+        }
+    }
+
     public static native void nativeSetMetricsEnabled(boolean enabled);
 }