Re-land: base: Implement browser process support for discardable memory.

content/test/blink_test_environment.cc

Index: content/test/blink_test_environment.cc
diff --git a/content/test/blink_test_environment.cc b/content/test/blink_test_environment.cc
index 816983c71db0d92216207b7c9d4ed9d202e25ca3..16b35a62c52ea220c704845e487c0ae7987ccc2d 100644
--- a/content/test/blink_test_environment.cc
+++ b/content/test/blink_test_environment.cc
@@ -10,6 +10,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_tokenizer.h"
+#include "base/test/test_discardable_memory_shmem_allocator.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/user_agent.h"
@@ -67,6 +68,9 @@ class TestEnvironment {
     // TestBlinkWebUnitTestSupport must be instantiated after MessageLoopType.
     blink_test_support_.reset(new TestBlinkWebUnitTestSupport);
     content_initializer_.reset(new content::TestContentClientInitializer());
+
+    base::DiscardableMemoryShmemAllocator::SetInstance(
+        &discardable_memory_allocator_);
   }
 
   ~TestEnvironment() {
@@ -80,6 +84,7 @@ class TestEnvironment {
   scoped_ptr<MessageLoopType> main_message_loop_;
   scoped_ptr<TestBlinkWebUnitTestSupport> blink_test_support_;
   scoped_ptr<TestContentClientInitializer> content_initializer_;
+  base::TestDiscardableMemoryShmemAllocator discardable_memory_allocator_;
 };
 
 TestEnvironment* test_environment;