Improvements/additions to SkImageCache/SkLazyPixelRef.

SkPurgeableImageCache:
New image cache that uses virtual memory to store the pixels. Combines
features of SkAshmemImageCache (which has been removed) with SkPurgeableMemoryBlock, which has android and Mac versions.

SkImageCache:
Modified the API. pinCache now returns a status out parameter which
states whether the pinned memory retained the old data. This allows
allocAndPinCache to only be used for allocations.
Add a new debug only interface to purge unpinned data.
Updates to documentation, clarifying behavior.
Changed CachedStatus to MemoryStatus

SkLruImageCache:
Implement the new function purgeAllUnpinnedCaches and change implementation
of pinCache for the new behavior.

SkLazyPixelRef:
Rewrite onLockPixels to account for the new behavior of pinCache.

BitmapFactoryTest:
Test the new SkPurgeableImageCache.
Write tests which directly test the SkImageCaches.
Create a larger bitmap, since some of the SkImageCaches are designed
to handle large bitmaps.

bench_ and render_pictures:
Consolidate lazy_decode_bitmap into one function.
Allow using a flag to specify using the purgeable image cache.
Clean up some #includes.

Review URL: https://codereview.chromium.org/12433020

git-svn-id: http://skia.googlecode.com/svn/trunk@8207 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/lazy/SkBitmapFactory.h b/include/lazy/SkBitmapFactory.h
index bebd3a7..eb427ee 100644
--- a/include/lazy/SkBitmapFactory.h
+++ b/include/lazy/SkBitmapFactory.h
@@ -67,20 +67,29 @@
     bool installPixelRef(SkData*, SkBitmap*);
 
     /**
-     *  A function for selecting an SkImageCache to use based on an SkImage::Info.
+     *  An object for selecting an SkImageCache to use based on an SkImage::Info.
      */
-    typedef SkImageCache* (*CacheSelector)(const SkImage::Info&);
+    class CacheSelector : public SkRefCnt {
+
+    public:
+        /**
+         *  Return an SkImageCache to use based on the provided SkImage::Info. If the caller decides
+         *  to hang on to the result, it will call ref, so the implementation should not add a ref
+         *  as a result of this call.
+         */
+        virtual SkImageCache* selectCache(const SkImage::Info&) = 0;
+    };
 
     /**
      *  Set the function to be used to select which SkImageCache to use. Mutually exclusive with
      *  fImageCache.
      */
-    void setCacheSelector(CacheSelector);
+    void setCacheSelector(CacheSelector*);
 
 private:
-    DecodeProc    fDecodeProc;
-    SkImageCache* fImageCache;
-    CacheSelector fCacheSelector;
+    DecodeProc     fDecodeProc;
+    SkImageCache*  fImageCache;
+    CacheSelector* fCacheSelector;
 };
 
 #endif // SkBitmapFactory_DEFINED