Plugin Power Saver: Implement pixel tests for plugin placeholders.

ppapi/tests/power_saver_test_plugin.cc

Index: ppapi/tests/power_saver_test_plugin.cc
diff --git a/ppapi/tests/power_saver_test_plugin.cc b/ppapi/tests/power_saver_test_plugin.cc
index 521fafa8a960029542d160834abbbf9192a0ffdd..90727f8000ddd84388ac0097085002b7ba4bf6ce 100644
--- a/ppapi/tests/power_saver_test_plugin.cc
+++ b/ppapi/tests/power_saver_test_plugin.cc
@@ -57,10 +57,13 @@ class PowerSaverTestInstance : public pp::Instance {
     if (image.is_null())
       return;
 
-    // Draw black and white stripes to present an "interesting" keyframe.
+    // Draw blue and green checkerboard pattern to show "interesting" keyframe.
+    int square_size = 8;
     for (int y = 0; y < view_.GetRect().size().height(); ++y) {
       for (int x = 0; x < view_.GetRect().size().width(); ++x) {
-        uint32_t color = x % 2 ? 0xFF0000FF : 0xFFFFFFFF;
+        int x_square = x / square_size;
+        int y_square = y / square_size;
+        uint32_t color = ((x_square + y_square) % 2) ? 0xFF0000FF : 0xFF00FF00;
         *image.GetAddr32(pp::Point(x, y)) = color;
       }
     }