Fix a crash in the Cronet integration when handling empty responses.

integration/cronet/src/main/java/com/bumptech/glide/integration/cronet/BufferQueue.java

@@ -68,21 +68,21 @@ private static long bufferSizeHeuristic(UrlResponseInfo info) {
       final Map<String, List<String>> headers = info.getAllHeaders();
       if (headers.containsKey(CONTENT_LENGTH)) {
         long contentLength = Long.parseLong(headers.get(CONTENT_LENGTH).get(0));
-        boolean isCompressed =
+        boolean isIdentity =
             !headers.containsKey(CONTENT_ENCODING)
                 || (headers.get(CONTENT_ENCODING).size() == 1
                     && "identity".equals(headers.get(CONTENT_ENCODING).get(0)));
-        if (isCompressed) {
-          // We have to guess at the uncompressed size. In the future, consider guessing a
-          // compression ratio based on the content-type and content-encoding. For now,
-          // assume 2.
-          return 2 * contentLength;
-        } else {
+        if (isIdentity) {
           // In this case, we know exactly how many bytes we're going to get, so we can
           // size our buffer perfectly. However, we still have to call read() for the last time,
           // even when we know there shouldn't be any more bytes coming. To avoid allocating another
           // buffer for that case, add one more byte than we really need.
           return contentLength + 1;
+        } else {
+          // We have to guess at the uncompressed size. In the future, consider guessing a
+          // compression ratio based on the content-type and content-encoding. For now,
+          // assume 2.
+          return 2 * contentLength + 1;
         }
       } else {
         // No content-length. This means we're either being sent a chunked response, or the

integration/cronet/src/test/java/com/bumptech/glide/integration/cronet/ChromiumUrlFetcherTest.java

@@ -83,6 +83,20 @@ public ByteBuffer answer(InvocationOnMock invocation) throws Throwable {
             anyString(), any(UrlRequest.Callback.class), any(Executor.class)))
         .thenReturn(mockUrlRequestBuilder);
     when(mockUrlRequestBuilder.build()).thenReturn(request);
+    org.mockito.Mockito.doAnswer(
+            new org.mockito.stubbing.Answer<Void>() {
+              @Override
+              public Void answer(org.mockito.invocation.InvocationOnMock invocation)
+                  throws Throwable {
+                ByteBuffer buffer = invocation.getArgument(0);
+                if (!buffer.hasRemaining()) {
+                  throw new IllegalArgumentException("ByteBuffer is already full.");
+                }
+                return null;
+              }
+            })
+        .when(request)
+        .read(any(ByteBuffer.class));
 
     glideUrl = new GlideUrl("http://www.google.com");
 
@@ -204,7 +218,9 @@ public List<Map.Entry<String, String>> getAllHeadersAsList() {
       public Map<String, List<String>> getAllHeaders() {
         ImmutableMap.Builder<String, List<String>> builder = ImmutableMap.builder();
         for (Map.Entry<String, String> entry : getAllHeadersAsList()) {
-          builder.put(entry.getKey(), ImmutableList.copyOf(entry.getValue().split(",")));
+          builder.put(
+              entry.getKey().toLowerCase(java.util.Locale.US),
+              ImmutableList.copyOf(entry.getValue().split(",")));
         }
         return builder.build();
       }
@@ -377,6 +393,20 @@ public void testRequestComplete_with200NotCancelledMatchingLength_callsCallbackW
         .isEqualTo(data);
   }
 
+  @Test
+  public void testRequestComplete_with200NotCancelledZeroLength_callsCallbackWithEmptyData()
+      throws Exception {
+    ByteBuffer expected = ByteBuffer.allocateDirect(0);
+    ArgumentCaptor<ByteBuffer> captor = ArgumentCaptor.forClass(ByteBuffer.class);
+
+    fetcher.loadData(Priority.LOW, callback);
+    succeed(getInfo(0, 200), urlRequestListenerCaptor.getValue(), expected.duplicate());
+
+    verify(callback, timeout(1000)).onDataReady(captor.capture());
+    ByteBuffer received = captor.getValue();
+    assertThat(received.remaining()).isEqualTo(0);
+  }
+
   private static Map<String, String> anyHeaders() {
     return anyMap();
   }