Revert of Add browser-wide discardable memory implementation. (patchset #23 id:910001 of https://codereview.chromium.org/531343002/)

Reason for revert:
Causes compile error.

http://build.chromium.org/p/chromium.linux/builders/Android%20Builder/builds/39232

../../base/memory/discardable_shared_memory.cc:208:5:error: ignoring return value of function declared with warn_unused_result attribute [-Werror,-Wunused-result]
    ftruncate(handle.fd, sizeof(SharedState));
    ^~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

Original issue's description:
> Add browser-wide discardable memory implementation.
>
> This provides a platform agnostic implementation of discardable
> memory based on shared memory. Managment of discardable memory is
> moved to the browser process instead of being local to each renderer.
> This provides much better control over chromium's total discardable
> memory usage.
>
> A round-trip to the browser IO thread is necessary for a renderer
> to allocate a new discardable memory segment but the cost of this
> can be reduced by maintaining free lists on the renderer side and
> have discardable memory instances share the same discardable
> memory segment. The implementation of this optimization is left as
> a follow up.
>
> Note: while the general implementation is platform agnostic, it
> takes advantage of the ftruncate syscall available on Posix
> platforms. This syscall makes it possible to release discardable
> memory segments immediately to the OS from the browser process.
>
> BUG=381178,400423,422953
> TEST=base_unittests --gtest_filter=DiscardableMemoryTests*, base_unittests --gtest_filter=DiscardableSharedMemory.*, content_unittests --gtest_filter=HostDiscardableSharedMemoryManagerTest.*
>
> Committed: https://crrev.com/2ac2d83d86b0206b908eea0d6e1002850d238a88
> Cr-Commit-Position: refs/heads/master@{#301152}

TBR=skuhne@chromium.org,rmcilroy@chromium.org,danakj@chromium.org,rsesek@chromium.org,nasko@chromium.org,reveman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=381178,400423,422953

Review URL: https://codereview.chromium.org/678603003

Cr-Commit-Position: refs/heads/master@{#301156}

0 files changed, 0 insertions, 0 deletions