Make SkStream *not* ref counted.

SkStream is a stateful object, so it does not make sense for it to have
multiple owners. Make SkStream inherit directly from SkNoncopyable.

Update methods which previously called SkStream::ref() (e.g.
SkImageDecoder::buildTileIndex() and SkFrontBufferedStream::Create(),
which required the existing owners to call SkStream::unref()) to take
ownership of their SkStream parameters and delete when done (including
on failure).

Switch all SkAutoTUnref<SkStream>s to SkAutoTDelete<SkStream>s. In some
cases this means heap allocating streams that were previously stack
allocated.

Respect ownership rules of SkTypeface::CreateFromStream() and
SkImageDecoder::buildTileIndex().

Update the comments for exceptional methods which do not affect the
ownership of their SkStream parameters (e.g.
SkPicture::CreateFromStream() and SkTypeface::Deserialize()) to be
explicit about ownership.

Remove test_stream_life, which tested that buildTileIndex() behaved
correctly when SkStream was a ref counted object. The test does not
make sense now that it is not.

In SkPDFStream, remove the SkMemoryStream member. Instead of using it,
create a new SkMemoryStream to pass to fDataStream (which is now an
SkAutoTDelete).

Make other pdf rasterizers behave like SkPDFDocumentToBitmap.

SkPDFDocumentToBitmap delete the SkStream, so do the same in the
following pdf rasterizers:

SkPopplerRasterizePDF
SkNativeRasterizePDF
SkNoRasterizePDF

Requires a change to Android, which currently treats SkStreams as ref
counted objects.

Review URL: https://codereview.chromium.org/849103004

4 files changed, 21 insertions, 14 deletions

diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index a0bcd33c7b..4dfd3c24e0 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -243,6 +243,8 @@ public:
      * The built index will be saved in the decoder, and the image size will
      * be returned in width and height.
      *
+     * Takes ownership of the SkStreamRewindable, on success or failure.
+     *
      * Return true for success or false on failure.
      */
     bool buildTileIndex(SkStreamRewindable*, int *width, int *height);
@@ -307,11 +309,9 @@ protected:
     // must be overridden in subclasses. This guy is called by decode(...)
     virtual Result onDecode(SkStream*, SkBitmap* bitmap, Mode) = 0;
 
-    // If the decoder wants to support tiled based decoding,
-    // this method must be overridden. This guy is called by buildTileIndex(...)
-    virtual bool onBuildTileIndex(SkStreamRewindable*, int* /*width*/, int* /*height*/) {
-        return false;
-    }
+    // If the decoder wants to support tiled based decoding, this method must be overridden.
+    // This is called by buildTileIndex(...)
+    virtual bool onBuildTileIndex(SkStreamRewindable*, int* /*width*/, int* /*height*/);
 
     // If the decoder wants to support tiled based decoding,
     // this method must be overridden. This guy is called by decodeRegion(...)
diff --git a/include/core/SkPicture.h b/include/core/SkPicture.h
index 80c3ca30a1..5b2f7a99f7 100644
--- a/include/core/SkPicture.h
+++ b/include/core/SkPicture.h
@@ -80,7 +80,7 @@ public:
 
     /**
      *  Recreate a picture that was serialized into a stream.
-     *  @param SkStream Serialized picture data.
+     *  @param SkStream Serialized picture data. Ownership is unchanged by this call.
      *  @param proc Function pointer for installing pixelrefs on SkBitmaps representing the
      *              encoded bitmap data from the stream.
      *  @return A new SkPicture representing the serialized data, or NULL if the stream is
diff --git a/include/core/SkStream.h b/include/core/SkStream.h
index abd9f92403..028c5c1a4d 100644
--- a/include/core/SkStream.h
+++ b/include/core/SkStream.h
@@ -36,17 +36,25 @@ class SkStreamMemory;
  *  no more data (at EOF or hit an error). The caller should *not* call again
  *  in hopes of fulfilling more of the request.
  */
-class SK_API SkStream : public SkRefCnt { //TODO: remove SkRefCnt
+class SK_API SkStream : public SkNoncopyable {
 public:
+    virtual ~SkStream() {}
+
+    /**
+     *  @deprecated
+     *  SkStream is no longer ref counted, but we leave this here for staging.
+     */
+    void unref() {
+        SkDebugf("SkStream is no longer ref counted!");
+    }
+
     /**
      *  Attempts to open the specified file, and return a stream to it (using
-     *  mmap if available). On success, the caller must call unref() on the
-     *  returned object. On failure, returns NULL.
+     *  mmap if available). On success, the caller is responsible for deleting.
+     *  On failure, returns NULL.
      */
     static SkStreamAsset* NewFromFile(const char path[]);
 
-    SK_DECLARE_INST_COUNT(SkStream)
-
     /** Reads or skips size number of bytes.
      *  If buffer == NULL, skip size bytes, return how many were skipped.
      *  If buffer != NULL, copy size bytes into buffer, return how many were copied.
@@ -125,9 +133,6 @@ public:
     /** Returns the starting address for the data. If this cannot be done, returns NULL. */
     //TODO: replace with virtual const SkData* getData()
     virtual const void* getMemoryBase() { return NULL; }
-
-private:
-    typedef SkRefCnt INHERITED;
 };
 
 /** SkStreamRewindable is a SkStream for which rewind and duplicate are required. */
diff --git a/include/core/SkTypeface.h b/include/core/SkTypeface.h
index c2aa543ab2..ecf582bd88 100644
--- a/include/core/SkTypeface.h
+++ b/include/core/SkTypeface.h
@@ -145,6 +145,7 @@ public:
         to a typeface referring to the same font. If that font is not available,
         return null. If an instance is returned, the caller is responsible for
         calling unref() when they are done with it.
+        Does not affect ownership of SkStream.
      */
     static SkTypeface* Deserialize(SkStream*);
 
@@ -276,6 +277,7 @@ public:
      *  If ttcIndex is not null, it is set to the TrueTypeCollection index
      *  of this typeface within the stream, or 0 if the stream is not a
      *  collection.
+     *  The caller is responsible for deleting the stream.
      */
     SkStream* openStream(int* ttcIndex) const;