Avoid getLength in ico decoder.

src/images/SkImageDecoder_libbmp.cpp

Index: src/images/SkImageDecoder_libbmp.cpp
diff --git a/src/images/SkImageDecoder_libbmp.cpp b/src/images/SkImageDecoder_libbmp.cpp
index 6c5ae27c478a22e13b3b62d77e59f0776ad45b23..73e7a2014459417e713673e5ab64a55726153bbf 100644
--- a/src/images/SkImageDecoder_libbmp.cpp
+++ b/src/images/SkImageDecoder_libbmp.cpp
@@ -8,10 +8,11 @@
 
 
 #include "bmpdecoderhelper.h"
+#include "SkColorPriv.h"
 #include "SkImageDecoder.h"
 #include "SkScaledBitmapSampler.h"
 #include "SkStream.h"
-#include "SkColorPriv.h"
+#include "SkStreamHelpers.h"
 #include "SkTDArray.h"
 #include "SkTRegistry.h"
 
@@ -96,31 +97,12 @@ bool SkBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
     // First read the entire stream, so that all of the data can be passed to
     // the BmpDecoderHelper.
 
-    // Byte length of all of the data.
-    size_t length;
     // Allocated space used to hold the data.
     SkAutoMalloc storage;
-
-    if (stream->hasLength()) {
-        length = stream->getLength();
-        void* dst = storage.reset(length);
-        if (stream->read(dst, length) != length) {
-            return false;
-        }
-    } else {
-        SkDynamicMemoryWStream tempStream;
-        // Arbitrary buffer size.
-        const size_t bufferSize = 256 * 1024; // 256 KB
-        char buffer[bufferSize];
-        length = 0;
-        do {
-            size_t bytesRead = stream->read(buffer, bufferSize);
-            tempStream.write(buffer, bytesRead);
-            length += bytesRead;
-            SkASSERT(tempStream.bytesWritten() == length);
-        } while (!stream->isAtEnd());
-        void* dst = storage.reset(length);
-        tempStream.copyTo(dst);
+    // Byte length of all of the data.
+    const size_t length = CopyStreamToStorage(&storage, stream);
+    if (0 == length) {
+        return 0;
     }
 
     const bool justBounds = SkImageDecoder::kDecodeBounds_Mode == mode;