Avoid getLength in ico decoder.

src/images/SkImageDecoder.cpp

Index: src/images/SkImageDecoder.cpp
diff --git a/src/images/SkImageDecoder.cpp b/src/images/SkImageDecoder.cpp
index a671607ef36f811695fd8fbe4831749a294634d6..a68e324d07e88833915e853cce1cdee5a47aa8d9 100644
--- a/src/images/SkImageDecoder.cpp
+++ b/src/images/SkImageDecoder.cpp
@@ -467,3 +467,44 @@ bool SkImageDecoder::DecodeStream(SkStream* stream, SkBitmap* bm,
     }
     return success;
 }
+
+/**
+ *  Copy the provided stream to memory allocated by storage.
+ *  Used by SkImageDecoder_libbmp and SkImageDecoder_libico.
+ *  @param storage Allocator to hold the memory. Will be reset to be large
+ *      enough to hold the entire stream. Upon successful return,
+ *      storage->get() will point to data holding the streams entire
+ *      contents.
+ *  @param stream SkStream to be copied into storage.
+ *  @return size_t Total number of bytes in the SkStream, which is also the
+ *      number of bytes pointed to by storage->get(). Returns 0 on failure.
+ */
+size_t copy_stream_to_storage(SkAutoMalloc* storage, SkStream* stream) {
+    SkASSERT(storage != NULL);
+    SkASSERT(stream != NULL);
+
+    if (stream->hasLength()) {
+        const size_t length = stream->getLength();
+        void* dst = storage->reset(length);
+        if (stream->read(dst, length) != length) {
+            return 0;
+        }
+        return length;
+    }
+
+    SkDynamicMemoryWStream tempStream;
+    // Arbitrary buffer size.
+    const size_t bufferSize = 256 * 1024; // 256KB
+    char buffer[bufferSize];
+    SkDEBUGCODE(size_t debugLength = 0;)
+    do {
+        size_t bytesRead = stream->read(buffer, bufferSize);
+        tempStream.write(buffer, bytesRead);
+        SkDEBUGCODE(debugLength += bytesRead);
+        SkASSERT(tempStream.bytesWritten() == debugLength);
+    } while (!stream->isAtEnd());
+    const size_t length = tempStream.bytesWritten();
+    void* dst = storage->reset(length);
+    tempStream.copyTo(dst);
+    return length;
+}