Added automated performance test to TileBenchmark

bug:5062896

Depends on external/webkit change:
https://android-git.corp.google.com/g/#change,125566

Loads pages from SD card, and scrolls through them reporting results. Added
contentInvalidateAll hidden WebView method, and made pageSwapCallback
extensible.

Change-Id: I9f7377aad6fd7c101177dde552a72357c8b4e400
diff --git a/tests/TileBenchmark/res/values/strings.xml b/tests/TileBenchmark/res/values/strings.xml
index 66972ac..c4fd189 100644
--- a/tests/TileBenchmark/res/values/strings.xml
+++ b/tests/TileBenchmark/res/values/strings.xml
@@ -71,8 +71,16 @@
     <string name="frames_per_second">Frames/sec</string>
     <!-- Portion of viewport covered by good tiles [CHAR LIMIT=15] -->
     <string name="viewport_coverage">Coverage</string>
+    <!-- Milliseconds taken to inval, and re-render the page [CHAR LIMIT=15] -->
+    <string name="render_millis">RenderMillis</string>
     <!-- Format string for stat value overlay [CHAR LIMIT=15] -->
     <string name="format_stat">%4.4f</string>
+
+    <!-- Format string for viewport position value overlay [CHAR LIMIT=25] -->
+    <string name="format_view_pos">View:(%1$d,%2$d)-(%3$d,%4$d)</string>
+    <!-- Format string for viewport position value overlay [CHAR LIMIT=25] -->
+    <string name="format_inval_pos">Inval:(%1$d,%2$d)-(%3$d,%4$d)</string>
+
     <!-- Format string for displaying aggregate stats+values (nr of valid tiles,
     etc.) [CHAR LIMIT=20] -->
     <string name="format_stat_name">%1$-20s %2$3d</string>