android: Build against NDK prebuilts, not system libraries.

android: Build against NDK prebuilts, not system libraries.

To allow the chromium WebView to build unbundled, we need to stop
linking to system libraries and instead link to the prebuilt libraries
in the NDK.

All modules compiled for target now specify LOCAL_SDK_VERSION with a
valid version of the SDK (defaulting to 19, the oldest version on which
the WebView builds). This can be overridden with the generator flag
"aosp_sdk_version".

Instead of converting library flags of the form "-lfoo" to entries in
LOCAL_SHARED_LIBRARIES, which causes a dependency on the system version
of the library, simply pass these flags through in ldflags. The NDK
library path is set automatically if LOCAL_SDK_VERSION is defined and
the correct version of these libraries will be found.

BUG=chromium:409851
R=primiano@chromium.org, thakis@chromium.org

Committed: https://code.google.com/p/gyp/source/detail?r=1990

[Torne, 2014-09-15 13:56:01]

torne@chromium.org changed reviewers:
+ primiano@chromium.org, thakis@chromium.org

[Torne, 2014-09-15 13:56:01]

This passes the gyp tests for me locally (tryjob queued) but will require
changes to build/common.gypi in chromium at the same time as gyp is rolled,
because currently chromium uses the system version of stlport which does not
build cleanly when using the NDK. We can't switch chromium to the NDK stlport
without this change, though, so I think we are stuck doing the two together.

I'll prepare the chromium-side change and upload it before submitting this.

There are no functional changes to the way that the simple binaries built in the
gyp tests are produced (since they don't use the STL).

[Primiano Tucci (use gerrit), 2014-09-15 14:25:15]

LGTM

> I'll prepare the chromium-side change and upload it before submitting this.
Uh? Don't you want to submit this first, then roll and then just make the gyp
file changes in chromium in the same CL?

[Torne, 2014-09-15 14:26:30]

On 2014/09/15 14:25:15, Primiano Tucci wrote:
> LGTM
> 
> > I'll prepare the chromium-side change and upload it before submitting this.
> Uh? Don't you want to submit this first, then roll and then just make the gyp
> file changes in chromium in the same CL?

Yes, but I want to have the other change ready as well so that we don't leave
gyp in an unrollable state for too long.

[Torne, 2014-09-15 14:34:03]

Chromium-side change: https://codereview.chromium.org/571953002

[Nico, 2014-09-16 14:25:18]

lgtm

Once the webview builds against the NDK, can it just use the ninja gyp
generator?

[Torne, 2014-09-16 14:29:21]

On 2014/09/16 14:25:18, Nico (hiding) wrote:
> lgtm
> 
> Once the webview builds against the NDK, can it just use the ninja gyp
> generator?

Not immediately as we still have a little more work to complete to completely
decouple us from the android platform files (some options/cflags that aren't the
same, building java, and a few other bits) and there's still some discussion
about exactly what form our build should take afterward, but that's the goal,
yes.

Unfortunately we can't land this patch right now as we need to revert one of the
prerequisite chromium changes for size reasons in the short term. I'll revisit
this soon when that's resolved. Thanks for looking :)

[Torne, 2014-10-17 17:57:28]

This is now unblocked, I've relanded the dependent changes in chromium.

[Torne, 2014-10-17 17:58:32]

Committed patchset #1 (id:1) manually as 1990 (presubmit successful).