pdfviewer: (more code cleanup): class documentation and comments

experimental/PdfViewer/SkTrackDevice.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTrackDevice_DEFINED
 #define SkTrackDevice_DEFINED
 
 #include "SkBitmapDevice.h"
 #include "SkTracker.h"
 
+/** \class SkTrackDevice
+ *
+ *   A Track Device is used to track that callstack of an operation that affected some pixels.
+ *   It can be used with SampleApp to investigate bugs (CL not checked in yet).
+ *
+ */
 class SkTrackDevice : public SkBitmapDevice {
 public:
     SK_DECLARE_INST_COUNT(SkTrackDevice)
 
     SkTrackDevice(const SkBitmap& bitmap) : SkBitmapDevice(bitmap)
                                           , fTracker(NULL) {}
 
     SkTrackDevice(const SkBitmap& bitmap, const SkDeviceProperties& deviceProperties)
         : SkBitmapDevice(bitmap, deviceProperties)
         , fTracker(NULL) {}
@@ skipping 152 matching lines @@
         }
     }
 
 private:
     SkTracker* fTracker;
 
     typedef SkBitmapDevice INHERITED;
 };
 
 #endif  // SkTrackDevice_DEFINED