Rework thumbnails in activity manager.

We now only keep a thumbnail for the task, not for each
activity.  However if you use FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET,
we will make a new secondary thumbnail for that series of
activities.  There is a new API for the app to get these
secondary thumbnails.

Also set a default thumbnail size for non-xlarge screens
so we have thumbnails on phones.  (We need some smarter
code in the platform for computing the actual thumbnail
dimensions of the current device).  And add a test app
to show recent tasks + thumbnails.

Change-Id: Ic36759f6635522118a2cb7f156662229a610c492
diff --git a/tests/ActivityTests/AndroidManifest.xml b/tests/ActivityTests/AndroidManifest.xml
new file mode 100644
index 0000000..6fa27ed
--- /dev/null
+++ b/tests/ActivityTests/AndroidManifest.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2008 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.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.google.android.test.activity">
+    <uses-permission android:name="android.permission.GET_TASKS" />
+    <uses-permission android:name="android.permission.READ_FRAME_BUFFER" />
+    <application android:label="ActivityTest">
+        <activity android:name="ActivityTestMain">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>