Revert "cc: Add some diagnostic CHECKs for sw image cache crashes."

This reverts commit fb48059c.

Original change's description:
> cc: Add some diagnostic CHECKs for sw image cache crashes.
>
> Change a few DCHECKs to CHECKs to validate if some crashes are
> resulting from using unlocked images, or incorrectly unlocking them
> earlier.
>
> R=​enne@chromium.org, ericrk@chromium.org
>
> Bug: 802976
> Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: Ibe0b9ef6ac52e6fafc9fd2670e20a9eefac17234
> Reviewed-on: https://chromium-review.googlesource.com/979160
> Commit-Queue: Khushal <khushalsagar@chromium.org>
> Reviewed-by: enne <enne@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#545724}

TBR=enne@chromium.org,khushalsagar@chromium.org,ericrk@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 826208
Change-Id: I152d1354ba7f43b77ae95d6edcf9f579109f6d91
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/980720
Commit-Queue: Khushal <khushalsagar@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547482}

cc/tiles/software_image_decode_cache.cc

@@ -303,8 +303,7 @@ void SoftwareImageDecodeCache::UnrefImage(const CacheKey& key) {
   auto decoded_image_it = decoded_images_.Peek(key);
   DCHECK(decoded_image_it != decoded_images_.end());
   auto* entry = decoded_image_it->second.get();
-  // TODO(khushalsagar): Temp CHECK to diagnose crbug.com/802976.
-  CHECK_GT(entry->ref_count, 0);
+  DCHECK_GT(entry->ref_count, 0);
   if (--entry->ref_count == 0) {
     if (entry->is_budgeted)
       RemoveBudgetForImage(key, entry);

cc/tiles/software_image_decode_cache_utils.h

@@ -122,8 +122,7 @@ class SoftwareImageDecodeCacheUtils {
     sk_sp<SkImage> image() const {
       if (!memory)
         return nullptr;
-      // TODO(khushalsagar): Temp CHECK to diagnose crbug.com/802976.
-      CHECK(is_locked);
+      DCHECK(is_locked);
       return image_;
     }
     const SkSize& src_rect_offset() const { return src_rect_offset_; }