Enable allocator shim for Android
This is a follow-up to crrev.com/1719433002, which introduced the
shim for Android, and enables it by default by setting
use_experimental_allocator_shim=true for Android.
Build/Perf sheriffs heads up
----------------------------
If you see any build error or crash related with __wrap_malloc,
__wrap_free, __real_malloc, __real_free, etc this CL is to blame.
Performance considerations
------------------------
Binary size diff (GN, arm, static, official build): 24k
I did a mixture of local and trybots run to estimate the perf impact
of this change. Didn't get any conclusive data, everything I tried
seems in the same ballpark, below noise levels. More in details:
cc_perftests.PrepareTiles on a Nexus 4.
Rationale of the choice: in a previous CL (crbug.com/593344), this
benchmark revealed the presence of two mfences in the malloc path.
Results: https://goo.gl/8VC3Jp in the same ballpark.
page-cycler on Nexus 9 via trybots:
Results: http://goo.gl/J3i50a seems to suggest that this CL improves
both warm and cold times in most cases. I doubt it, more likely it's
noise.
All the other perf trybots failed. The perf waterfall seems to be in a
bad state in these days.
BUG=550886,598075
TEST=base_unittests --gtest_filter=AllocatorShimTest.*
TBR=thakis@chromium.org
Review URL: https://codereview.chromium.org/1875043003
Cr-Commit-Position: refs/heads/master@{#386386}
3 files changed
