Add functionality for changing WebView provider.

Make it possible to change WebView provider (through a Developer
setting) and kill all apps using the old provider.
This includes checking the signatures of the WebView providers to make
sure they are valid.

Now that we can change WebView provider through a setting it is possible
to change provider while some provider is being updated. Because of this
we now keep track of which provider should be in use in
WebViewUpdateService to make sure we use the correct provider at all
times.

We now also read WebView package meta data (name, package name, and
signature) from a separate xml file.

Main bug: crbug.com/546185

Bug: 25338573

Change-Id: I660fd1a40a5388f6569a06a7f0d029e8ff65945a
diff --git a/core/java/android/webkit/WebViewProviderResponse.aidl b/core/java/android/webkit/WebViewProviderResponse.aidl
new file mode 100644
index 0000000..9c884cc
--- /dev/null
+++ b/core/java/android/webkit/WebViewProviderResponse.aidl
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.webkit;
+
+parcelable WebViewProviderResponse;