android envsetup: Use gyp defines instead of env vars for sdk root and sdk tools.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index b6ef9385dcc3d6a424f52452d7b25e02d7378967..217e6e5e13c0cead4d779f4eaabb028c332507e9 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -1390,19 +1390,18 @@
              'android_host_arch%': '<!(uname -m)',
              # Android API-level of the SDK used for compilation.
              'android_sdk_version%': '19',
-             # Android SDK build tools (e.g. dx, aapt, aidl)
-             'android_sdk_tools%': '<!(/bin/echo -n ${ANDROID_SDK_TOOLS})',
              'host_os%': "<!(uname -s | sed -e 's/Linux/linux/;s/Darwin/mac/')",
           },
           # Copy conditionally-set variables out one scope.
           'android_ndk_root%': '<(android_ndk_root)',
           'android_sdk_root%': '<(android_sdk_root)',
           'android_sdk_version%': '<(android_sdk_version)',
-          'android_sdk_tools%': '<(android_sdk_tools)',
           'android_stlport_root': '<(android_ndk_root)/sources/cxx-stl/stlport',
           'host_os%': '<(host_os)',
 
           'android_sdk%': '<(android_sdk_root)/platforms/android-<(android_sdk_version)',
+          # Android SDK build tools (e.g. dx, aapt, aidl)
+          'android_sdk_tools%': '<(android_sdk_root)/build-tools/<(android_sdk_version).0.0',

[Torne, 2014/02/17 12:14:19]

I don't think this is correct; I think the current sdk tools version being
19.0.0 is only a coincidence and this isn't necessarily the same as
android_sdk_version. The tools are updated independently of the API level.

[Nico, 2014/02/17 16:20:21]

Are you sure? They were updated at the same time the last time:
https://codereview.chromium.org/63153014

frankf thought a similar patch was ok (
https://codereview.chromium.org/download/issue167643002_200001.diff )

(I'm aware that in 18, the sdk tools folder was in 18.0.1 and not 18.0.0 – but
under the assumption that when one upgrades the sdk one wants to upgrade the sdk
tools too, having one reference the other still seems better as this makes it
impossible to forget about one of them. And if ".0.0" is wrong in some version,
one will get a try error when upgrading the version variable but forgetting
about ".0.0".)

[Yaron, 2014/02/18 18:55:51]

Two things come to mind:
1) When we first getting the SDK tools to work, we had to rely on a specific
revision of SDK tools so Torne's point of them being revved independently is
true, however, we did rely more heavily on the SDK-provided tooling at the time.
2) The android build for third party apps are switching from ant to gradle.
However, since we have gyp, we've tried to fit best within that and so we've
minimized usage of android-provided build tools (not the binaries themselves
necessarily, but more how they're used). I could imagine them deprecating
support for old tools and we may want to keep our old ones limping along for a
time since we really don't use much.
 
Anyway, long story short, I agree it's coincidence and can maintain a separate
define in gyp.

 
           # Android API level 14 is ICS (Android 4.0) which is the minimum
           # platform requirement for Chrome on Android, we use it for native