weblayer: adds support for attribution tagging

Android-R adds an attribution tag to Context. This tag can be used to
identify what parts of an application are requesting/using services.
Chrome code assumes a single Context, and for WebLayer that Context is
the application context. WebLayer calls getApplicationContext() on the
Context supplied to it. This means the attribution tag set on the
Context supplied to WebLayer is lost.

This patch changes WebLayer so that the attribution tag of the supplied
Context is propagated to the Context used by Chrome/WebLayer. This gives
the user of WebLayer a way to attribute usage of system services to
WebLayer.

BUG=1085041
TEST=none

Change-Id: I65eeea60289e57d563875754231658466c37dddd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2361022Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799600}

weblayer/public/java/org/chromium/weblayer/WebLayer.java

@@ -91,7 +91,6 @@ public class WebLayer {
      */
     public static boolean isAvailable(Context context) {
         ThreadCheck.ensureOnUiThread();
-        context = context.getApplicationContext();
         return getWebLayerLoader(context).isAvailable();
     }
 
@@ -127,8 +126,7 @@ public class WebLayer {
             throws UnsupportedVersionException {
         ThreadCheck.ensureOnUiThread();
         checkAvailable(appContext);
-        appContext = appContext.getApplicationContext();
-        getWebLayerLoader(appContext).loadAsync(appContext, callback);
+        getWebLayerLoader(appContext).loadAsync(callback);
     }
 
     /**
@@ -150,13 +148,12 @@ public class WebLayer {
     public static WebLayer loadSync(@NonNull Context appContext)
             throws UnsupportedVersionException {
         ThreadCheck.ensureOnUiThread();
-        appContext = appContext.getApplicationContext();
         checkAvailable(appContext);
-        return getWebLayerLoader(appContext).loadSync(appContext);
+        return getWebLayerLoader(appContext).loadSync();
     }
 
-    private static WebLayerLoader getWebLayerLoader(Context appContext) {
-        if (sLoader == null) sLoader = new WebLayerLoader(appContext);
+    private static WebLayerLoader getWebLayerLoader(Context context) {
+        if (sLoader == null) sLoader = new WebLayerLoader(context);
         return sLoader;
     }
 
@@ -167,7 +164,6 @@ public class WebLayer {
     static WebLayer getLoadedWebLayer(@NonNull Context appContext)
             throws UnsupportedVersionException {
         ThreadCheck.ensureOnUiThread();
-        appContext = appContext.getApplicationContext();
         checkAvailable(appContext);
         return getWebLayerLoader(appContext).getLoadedWebLayer();
     }
@@ -186,7 +182,6 @@ public class WebLayer {
      */
     public static int getSupportedMajorVersion(@NonNull Context context) {
         ThreadCheck.ensureOnUiThread();
-        context = context.getApplicationContext();
         return getWebLayerLoader(context).getMajorVersion();
     }
 
@@ -214,7 +209,6 @@ public class WebLayer {
     @NonNull
     public static String getSupportedFullVersion(@NonNull Context context) {
         ThreadCheck.ensureOnUiThread();
-        context = context.getApplicationContext();
         return getWebLayerLoader(context).getVersion();
     }
 
@@ -245,18 +239,27 @@ public class WebLayer {
         private final int mMajorVersion;
         private final String mVersion;
         private boolean mIsLoadingAsync;
+        private Context mContext;
 
         /**
          * Creates WebLayerLoader. This does a minimal amount of loading
          */
-        public WebLayerLoader(@NonNull Context appContext) {
+        public WebLayerLoader(@NonNull Context context) {
             boolean available = false;
             int majorVersion = -1;
             String version = "<unavailable>";
+            // Use the application context as the supplied context may have a shorter lifetime.
+            mContext = context.getApplicationContext();
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R
+                    && context.getAttributionTag() != null) {
+                // Getting the application context means we lose any attribution. Use the
+                // attribution tag from the supplied context so that embedders have a way to set an
+                // attribution tag.
+                mContext = mContext.createAttributionContext(context.getAttributionTag());
+            }
             try {
-                Class factoryClass =
-                        getOrCreateRemoteClassLoader(appContext)
-                                .loadClass("org.chromium.weblayer_private.WebLayerFactoryImpl");
+                Class factoryClass = getOrCreateRemoteClassLoader(mContext).loadClass(
+                        "org.chromium.weblayer_private.WebLayerFactoryImpl");
                 mFactory = IWebLayerFactory.Stub.asInterface(
                         (IBinder) factoryClass
                                 .getMethod("create", String.class, int.class, int.class)
@@ -291,7 +294,7 @@ public class WebLayer {
             return mVersion;
         }
 
-        public void loadAsync(@NonNull Context appContext, @NonNull Callback<WebLayer> callback) {
+        public void loadAsync(@NonNull Callback<WebLayer> callback) {
             if (mWebLayer != null) {
                 callback.onResult(mWebLayer);
                 return;
@@ -301,35 +304,33 @@ public class WebLayer {
                 return; // Already loading.
             }
             mIsLoadingAsync = true;
-            if (getIWebLayer(appContext) == null) {
+            if (getIWebLayer() == null) {
                 // Unable to create WebLayer. This generally shouldn't happen.
                 onWebLayerReady();
                 return;
             }
             try {
-                getIWebLayer(appContext)
-                        .loadAsync(ObjectWrapper.wrap(appContext),
-                                ObjectWrapper.wrap(getOrCreateRemoteContext(appContext)),
-                                ObjectWrapper.wrap(
-                                        (ValueCallback<Boolean>) result -> { onWebLayerReady(); }));
+                getIWebLayer().loadAsync(ObjectWrapper.wrap(mContext),
+                        ObjectWrapper.wrap(getOrCreateRemoteContext(mContext)),
+                        ObjectWrapper.wrap(
+                                (ValueCallback<Boolean>) result -> { onWebLayerReady(); }));
             } catch (Exception e) {
                 throw new APICallException(e);
             }
         }
 
-        public WebLayer loadSync(@NonNull Context appContext) {
+        public WebLayer loadSync() {
             if (mWebLayer != null) {
                 return mWebLayer;
             }
-            if (getIWebLayer(appContext) == null) {
+            if (getIWebLayer() == null) {
                 // Error in creating WebLayer. This generally shouldn't happen.
                 onWebLayerReady();
                 return null;
             }
             try {
-                getIWebLayer(appContext)
-                        .loadSync(ObjectWrapper.wrap(appContext),
-                                ObjectWrapper.wrap(getOrCreateRemoteContext(appContext)));
+                getIWebLayer().loadSync(ObjectWrapper.wrap(mContext),
+                        ObjectWrapper.wrap(getOrCreateRemoteContext(mContext)));
                 onWebLayerReady();
                 return mWebLayer;
             } catch (Exception e) {
@@ -342,7 +343,7 @@ public class WebLayer {
         }
 
         @Nullable
-        private IWebLayer getIWebLayer(@NonNull Context appContext) {
+        private IWebLayer getIWebLayer() {
             if (mIWebLayer != null) return mIWebLayer;
             if (!mAvailable) return null;
             try {
@@ -560,8 +561,8 @@ public class WebLayer {
         }
     }
 
-    /* package */ static IWebLayer getIWebLayer(Context appContext) {
-        return getWebLayerLoader(appContext).getIWebLayer(appContext);
+    /* package */ static IWebLayer getIWebLayer(Context context) {
+        return getWebLayerLoader(context).getIWebLayer();
     }
 
     /**