Plugin Power Saver: Implement pixel tests for plugin placeholders.

ppapi/tests/power_saver_test_plugin.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 
 #include "ppapi/cpp/graphics_2d.h"
 #include "ppapi/cpp/image_data.h"
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/module.h"
@@ skipping 39 matching lines @@
     Paint();
   }
 
  private:
   void Paint() {
     pp::ImageData image(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
                         view_.GetRect().size(), true);
     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.
+    const int kSquareSizePixels = 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 / kSquareSizePixels;
+        int y_square = y / kSquareSizePixels;
+        uint32_t color = ((x_square + y_square) % 2) ? 0xFF0000FF : 0xFF00FF00;
         *image.GetAddr32(pp::Point(x, y)) = color;
       }
     }
 
     device_context_.ReplaceContents(&image);
     device_context_.Flush(
         pp::CompletionCallback(&DummyCompletionCallback, nullptr));
   }
 
   pp::View view_;
@@ skipping 10 matching lines @@
   }
 };
 
 namespace pp {
 
 Module* CreateModule() {
   return new PowerSaverTestModule();
 }
 
 }  // namespace pp