OOP-R: Lower Transfer Cache Limits for low-end Android

Currently, the OOP-R transfer cache has a 4MB cache on low-end. As the
primary use of this cache turned out to be images, with only small
additional colorspace and path caches, we should make this more closely
match the discardable image cache's low-end size (512KB).

Chosing 768KB to allow for small amounts of additional cache items.

R=khushalsagar

Bug: 866737
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I2f04ce5bac3d2d94bb73bfd877169947d7aae64d
Reviewed-on: https://chromium-review.googlesource.com/1147759Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577603}

gpu/command_buffer/service/service_transfer_cache.cc

@@ -24,8 +24,11 @@ static size_t kMaxCacheEntries = 2000;
 
 size_t CacheSizeLimit() {
   size_t memory_usage = 128 * 1024 * 1024;
-  if (base::SysInfo::IsLowEndDevice())
-    memory_usage = 4 * 1024 * 1024;
+  if (base::SysInfo::IsLowEndDevice()) {
+    // Based on the 512KB limit used for discardable images in non-OOP-R, but
+    // gives an extra 256KB to allow for additional (non-image) cache items.
+    memory_usage = 768 * 1024;
+  }
   return memory_usage;
 }