Correct memory allocators in paint_op_buffer_fuzzer

Properly have 'new' terminate on oom and set the discardable memory
allocator so that it can be used.

Bug: chromium:993654
Change-Id: I9d26135447f8174d528ac1e44dc6165cfcf93233
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1754530Reviewed-by: enne <enne@chromium.org>
Commit-Queue: Ben Wagner <bungeman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#687412}

cc/paint/BUILD.gn

@@ -118,6 +118,7 @@ fuzzer_test("paint_op_buffer_fuzzer") {
   libfuzzer_options = [ "max_len=4096" ]
 
   deps = [
+    "//base/test:test_support",
     "//cc:test_support",
     "//cc/paint",
     "//components/viz/test:test_support",

cc/paint/paint_op_buffer_fuzzer.cc

@@ -6,6 +6,8 @@
 #include <stdint.h>
 
 #include "base/command_line.h"
+#include "base/process/memory.h"
+#include "base/test/test_discardable_memory_allocator.h"
 #include "cc/paint/paint_cache.h"
 #include "cc/paint/paint_op_buffer.h"
 #include "cc/test/transfer_cache_test_helper.h"
@@ -20,7 +22,16 @@ struct Environment {
     // Disable noisy logging as per "libFuzzer in Chrome" documentation:
     // testing/libfuzzer/getting_started.md#Disable-noisy-error-message-logging.
     logging::SetMinLogLevel(logging::LOG_FATAL);
+
+    base::EnableTerminationOnOutOfMemory();
+    base::DiscardableMemoryAllocator::SetInstance(
+        &discardable_memory_allocator);
   }
+
+  ~Environment() { base::DiscardableMemoryAllocator::SetInstance(nullptr); }
+
+ private:
+  base::TestDiscardableMemoryAllocator discardable_memory_allocator;
 };
 
 class FontSupport : public gpu::ServiceFontManager::Client {