Record UMA stats for Blink decoded image types

Source/platform/graphics/BitmapImage.cpp

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 322 matching lines @@
     return m_frameCount;
 }
 
 bool BitmapImage::isSizeAvailable()
 {
     if (m_sizeAvailable)
         return true;
 
     m_sizeAvailable = m_source.isSizeAvailable();
 
+    if (m_sizeAvailable && (size().width() > 1 || size().height() > 1)) {

[Noel Gordon, 2015/08/01 02:33:06]

Yes better.  Let's define a static inline hasVisibleImageSize(size()) helper to
document the visible size thing.

In that helper, should it be the conjunction, viz., size().width() > N _&&_
size().height() > N ?

N=1 is obvious I suppose, but what value of N should we use to declare an image
visible?  N=6,8,10,...?  Consider the smallest box that could be visible _and_
meaningful to a user.

[urvang, 2015/08/04 20:21:16]

Done.
No, we require || operator because 1x100 as well as 100x1 sized images are
visible, for example.
Any image larger than 1x1 would be visible. So, N=1 is appropriate.

+        String fileExtention = m_source.filenameExtension();
+        DecodedImageType type =
+            fileExtention == "jpg"  ? ImageJPEG :
+            fileExtention == "png"  ? ImagePNG :
+            fileExtention == "gif"  ? ImageGIF :
+            fileExtention == "webp" ? ImageWebP :
+            fileExtention == "ico"  ? ImageICO :
+            fileExtention == "bmp"  ? ImageBMP :
+            ImageUnknown;
+        Platform::current()->histogramEnumeration("Blink.DecodedImageType", type, DecodedImageTypeMax + 1);
+    }
+
     return m_sizeAvailable;
 }
 
 bool BitmapImage::ensureFrameIsCached(size_t index)
 {
     if (index >= frameCount())
         return false;
 
     if (index >= m_frames.size() || !m_frames[index].m_frame)
         cacheFrame(index);
@@ skipping 290 matching lines @@
     destroyDecodedDataIfNecessary();
 
     // We need to draw this frame if we advanced to it while not skipping, or if
     // while trying to skip frames we hit the last frame and thus had to stop.
     if (skippingFrames != advancedAnimation)
         imageObserver()->animationAdvanced(this);
     return advancedAnimation;
 }
 
 } // namespace blink