[Paint Preview] Try to reduce tile pop-in, by increasing parallel requests

We are seeing some pretty bad pop-in sometimes. Try to more eagerly request bitmaps.

Change-Id: I4fb249a4b72b4f9034df15c5d4ef4ba0ef0a01aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519577
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Mehran Mahmoudi <mahmoudi@chromium.org>
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824072}

components/paint_preview/player/android/player_compositor_delegate_android.cc

@@ -31,9 +31,8 @@ namespace paint_preview {
 
 namespace {
 
-// To minimize peak memory usage limit the number of concurrent bitmap requests
-// to 4.
-constexpr size_t kMaxParallelBitmapRequests = 4;
+// To minimize peak memory usage limit the number of concurrent bitmap requests.
+constexpr size_t kMaxParallelBitmapRequests = 6;
 
 ScopedJavaLocalRef<jobjectArray> ToJavaUnguessableTokenArray(
     JNIEnv* env,