[Android] Allow more support for experimentation with SDK.

build/android/envsetup_functions.sh

 #!/bin/bash
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Defines functions for envsetup.sh which sets up environment for building
 # Chromium on Android.  The build can be either use the Android NDK/SDK or
 # android source tree.  Each has a unique init function which calls functions
 # prefixed with "common_" that is common for both environment setups.
@@ skipping 200 matching lines @@
 # environment ANDROID_NDK_ROOT must be set to Android NDK's root path.  The
 # ANDROID_SDK_ROOT only needs to be set to override the default SDK which is in
 # the tree under $ROOT/src/third_party/android_tools/sdk.
 # To build Chromium for Android with NDK/SDK follow the steps below:
 #  > export ANDROID_NDK_ROOT=<android ndk root>
 #  > export ANDROID_SDK_ROOT=<android sdk root> # to override the default sdk
 #  > . build/android/envsetup.sh
 #  > make
 ################################################################################
 sdk_build_init() {
-  export ANDROID_SDK_VERSION=18
-  export ANDROID_SDK_BUILD_TOOLS_VERSION=18.0.1
 
-  # If ANDROID_NDK_ROOT is set when envsetup is run, use the ndk pointed to by
-  # the environment variable.  Otherwise, use the default ndk from the tree.
+  # Allow the caller to override a few environment variables. If any of them is
+  # unset, we default to a sane value that's known to work. This allows for
+  # experimentation with a custom SDK.
   if [[ -z "${ANDROID_NDK_ROOT}" || ! -d "${ANDROID_NDK_ROOT}" ]]; then

[Isaac (away), 2013/08/13 02:19:54]

How about we remove the -d check (checks the variable points to a valid
directory)?  We could trust the caller to have a proper environment.

     export ANDROID_NDK_ROOT="${CHROME_SRC}/third_party/android_tools/ndk/"
   fi
-
-  # If ANDROID_SDK_ROOT is set when envsetup is run, and if it has the
-  # right SDK-compatible directory layout, use the sdk pointed to by the
-  # environment variable.  Otherwise, use the default sdk from the tree.
+  if [[ -z "${ANDROID_SDK_VERSION}" ]]; then

[Isaac (away), 2013/08/13 02:19:54]

technically quotes aren't needed in a double bracket test, but it's fine, and
matches the style of the file.

+    export ANDROID_SDK_VERSION=18
+  fi
   local sdk_suffix=platforms/android-${ANDROID_SDK_VERSION}
   if [[ -z "${ANDROID_SDK_ROOT}" || \
        ! -d "${ANDROID_SDK_ROOT}/${sdk_suffix}" ]]; then

[Isaac (away), 2013/08/13 02:19:54]

ditto on -d here

[Yaron, 2013/08/13 02:24:46]

I actually like this. It helped me catch an issue where my custom SDK had a
slightly different folder structure.

     export ANDROID_SDK_ROOT="${CHROME_SRC}/third_party/android_tools/sdk/"
   fi
+  if [[ -z "${ANDROID_SDK_BUILD_TOOLS_VERSION}" ]]; then
+    export ANDROID_SDK_BUILD_TOOLS_VERSION=18.0.1
+  fi
 
   unset ANDROID_BUILD_TOP
 
   # Set default target.
   export TARGET_PRODUCT="${TARGET_PRODUCT:-trygon}"
 
   # Unset toolchain so that it can be set based on TARGET_PRODUCT.
   # This makes it easy to switch between architectures.
   unset ANDROID_TOOLCHAIN
 
@@ skipping 68 matching lines @@
   export GYP_DEFINES="${DEFINES}"
 
   export GYP_GENERATORS="android"
 
   export GYP_GENERATOR_FLAGS="${GYP_GENERATOR_FLAGS} default_target=All"
   export GYP_GENERATOR_FLAGS="${GYP_GENERATOR_FLAGS} limit_to_target_all=1"
   export GYP_GENERATOR_FLAGS="${GYP_GENERATOR_FLAGS} auto_regeneration=0"
 
   export CHROMIUM_GYP_FILE="${CHROME_SRC}/android_webview/all_webview.gyp"
 }