Adding possibility to override android{32,64}_ndk_api_level.

WebRTC wants to link with libaaudio.so (to test the new library) but
the current code is pinning the NDK api to 16 on 32 bits platforms and
to 21 on 64 bits platforms.

This CL makes this value configurable.

Bug: webrtc:8756
Change-Id: I98bd7c8ccb302c4bf81a29d356eea8c29bfd692d
Reviewed-on: https://chromium-review.googlesource.com/866841
Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#529674}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1e9a3dd04b85bc5cab0dfba997fa2a4b8f4f153a

config/android/BUILD.gn

@@ -52,25 +52,25 @@ config("compiler") {
   # calculation in //build/config/android/config.gni
   if (current_cpu == "arm") {
     abi_target = "arm-linux-androideabi"
-    compile_api_level = 16
+    compile_api_level = android32_ndk_api_level
   } else if (current_cpu == "x86") {
     abi_target = "i686-linux-android"
-    compile_api_level = 16
+    compile_api_level = android32_ndk_api_level
   } else if (current_cpu == "arm64") {
     abi_target = "aarch64-linux-android"
-    compile_api_level = 21
+    compile_api_level = android64_ndk_api_level
   } else if (current_cpu == "x64") {
     # Place holder for x64 support, not tested.
     # TODO: Enable clang support for Android x64. http://crbug.com/539781
     abi_target = "x86_64-linux-android"
-    compile_api_level = 21
+    compile_api_level = android64_ndk_api_level
   } else if (current_cpu == "mipsel") {
     abi_target = "mipsel-linux-android"
-    compile_api_level = 16
+    compile_api_level = android32_ndk_api_level
   } else if (current_cpu == "mips64el") {
     # Place holder for mips64 support, not tested.
     abi_target = "mips64el-linux-android"
-    compile_api_level = 21
+    compile_api_level = android64_ndk_api_level
   } else {
     assert(false, "Architecture not supported")
   }

config/android/config.gni

@@ -23,6 +23,12 @@ if (is_android) {
     # The main purpose of this argument is to avoid having to maintain 2
     # repositories to support both public only and internal builds.
     enable_chrome_android_internal = has_chrome_android_internal
+
+    # Android API level for 32 bits platforms
+    android32_ndk_api_level = 16
+
+    # Android API level for 64 bits platforms
+    android64_ndk_api_level = 21
   }
 
   if (enable_chrome_android_internal) {
@@ -253,21 +259,18 @@ if (is_android) {
 
   # Subdirectories inside android_ndk_root that contain the sysroot for the
   # associated platform.
-  _android_api_level = 16
   x86_android_sysroot_subdir =
-      "platforms/android-${_android_api_level}/arch-x86"
+      "platforms/android-${android32_ndk_api_level}/arch-x86"
   arm_android_sysroot_subdir =
-      "platforms/android-${_android_api_level}/arch-arm"
+      "platforms/android-${android32_ndk_api_level}/arch-arm"
   mips_android_sysroot_subdir =
-      "platforms/android-${_android_api_level}/arch-mips"
-
-  _android64_api_level = 21
+      "platforms/android-${android32_ndk_api_level}/arch-mips"
   x86_64_android_sysroot_subdir =
-      "platforms/android-${_android64_api_level}/arch-x86_64"
+      "platforms/android-${android64_ndk_api_level}/arch-x86_64"
   arm64_android_sysroot_subdir =
-      "platforms/android-${_android64_api_level}/arch-arm64"
+      "platforms/android-${android64_ndk_api_level}/arch-arm64"
   mips64_android_sysroot_subdir =
-      "platforms/android-${_android64_api_level}/arch-mips64"
+      "platforms/android-${android64_ndk_api_level}/arch-mips64"
 
   # Toolchain root directory for each build. The actual binaries are inside
   # a "bin" directory inside of these.