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    Reland (2) of: Allow base to depend on allocator · e97b9201
    primiano authored
    Reason for reland:
    Some targets (clearkeycdmadapter, osmesa) now fell in the state where
    they depend indirectly on base (which causes the removal of the default
    clib) but via a shared_library boundary (which does not propagate the
    replacement allocator / shim layer code).
    Fixing those targets by adding a direct base dependency.
    
    This causes a breakage in the main waterfall:
    https://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN/builds/10231
    
    Original CL description:
    > A smaller, yet key, step to move
    >
    > From: a situation where mainly executables (but not really) depend on
    > allocator, and base needs dependencies (to tcmalloc) to be injected
    > from content (which violates the ODR in component buids).
    >
    > To: a situation where only base depends on allocator and the other
    > targets get recursively the required linked flags.
    >
    > In essence this CL is a more gradual approach to the bigger
    > unreviewable crrev.com/1528013002.
    >
    > How is the transition handled?
    > ------------------------------
    > After this CL, the situation will be as follows:
    > From a build time perspective base will also depend on allocator.
    > This will not change anything substantial in static builds and introduce
    > yet another (temporary) ODR violation in Linux component builds.
    > The big change introduced by this CL is the fact that all the executable
    > targets that depend on base (virtualy all) will also get another
    > indirect dependency to allocator.
    >
    > In other words, after this CL executable targets will depend on
    > allocator for two reasons:
    >  - Because they have an explicit dependency to it (the one I am going to
    >    get rid of in the immediate future).
    >  - Because this new transitive path I am introducing in base.
    >
    > Rationale of this approach
    > --------------------------
    > This allows to restrict the critical changes in a smaller CL easier to
    > review, at the cost of the temporary double dependency on base.
    > The good things are:
    >  - If something will break, this CL will be very easy to revert.
    >  - The next cleanups will be straightforward.
    >  - We have now smoke tests (crrev.com/1577883002) that will help us
    >    realize if something goes wrong.
    >
    > Next steps
    > ----------
    > In the next CLs I will:
    >  - Remove the content -> base injection layer, and let base directly use
    >    the tcmalloc functions it needs.
    >  - Remove all the traces of USE_TCMALLOC outside of base.
    >  - Start cleaning up the hundreds use_allocator conditionals in the gyp
    >    files in a way which is easier to review and produce zero ninja diffs
    >    (see crrev.com/1583973002 as an example)
    >
    > Ninja diffs caused by this change
    > ---------------------------------
    >  ### Win, static build, GN:   https://paste.ee/p/hvcRp
    >  The missing targets (mostly tests) that previously were
    >  not depending on allocator, now get that by virtue of the transitive
    >  dependency.
    >
    >  ### Win, static build, GYP:  https://paste.ee/p/AGuKR
    >  As above. Just GYP seems to emit the ninja files in a different,
    >  inlined, format.
    >
    >  ### linux static build, GYP:  https://paste.ee/p/kmD7U
    >  As above. Plus the new targets also get the -Wl,-u (keep symbol)
    >  args as expected by allocator.gyp for the tcmalloc heap profiler.
    >
    >  ### linux shared build, GYP: https://paste.ee/p/FHHNR
    >  Nothing relevant. Just I moved the dependency to allocator from
    >  base_unittests to base, and that is the only thing that reflects in the
    >  ninja files.
    >
    > BUG=564618
    
    TBR=wfh@chromium.org,brettw@chromium.org,kbr@chromium.org
    BUG=564618
    
    Review URL: https://codereview.chromium.org/1616793003
    
    Cr-Commit-Position: refs/heads/master@{#370694}
    e97b9201