Use DiscardableMemoryManager on Android.

base/base.gypi

Index: base/base.gypi
diff --git a/base/base.gypi b/base/base.gypi
index 7f2d58fbce5075e0b81933a7913365f7a4df4345..8f36dc7ec16ee38fd50ea9900fad4da59d969e2b 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -314,8 +314,6 @@
           'memory/aligned_memory.h',
           'memory/discardable_memory.cc',
           'memory/discardable_memory.h',
-          'memory/discardable_memory_allocator_android.cc',
-          'memory/discardable_memory_allocator_android.h',
           'memory/discardable_memory_android.cc',
           'memory/discardable_memory_emulated.cc',
           'memory/discardable_memory_emulated.h',
@@ -797,6 +795,14 @@
               ['include', '^threading/platform_thread_linux\\.cc$'],
             ],
           }],
+          ['OS == "android" and _toolset == "target"', {
+            'sources': [
+              'memory/discardable_memory_allocation_ashmem_factory.cc',
+              'memory/discardable_memory_allocation_ashmem_factory.h',
+              'memory/discardable_memory_ashmem.cc',
+              'memory/discardable_memory_ashmem.h',
+            ],
+          }],
           ['OS == "android" and >(nacl_untrusted_build)==0', {
             'sources!': [
               'base_paths_posix.cc',