Android: make the top level Android makefile smarter.

Android.mk

Index: Android.mk
diff --git a/Android.mk b/Android.mk
index 5e94479f69d14e004f699e3ef4a208590559db13..3ba8d5c5b233beed0c921fc147b7cc03786ada93 100644
--- a/Android.mk
+++ b/Android.mk
@@ -8,8 +8,11 @@
 # which prevents the Android build system from mistakenly loading any other
 # Android.mk that may exist in the Chromium tree.
 
-ifdef CHROME_ANDROID_BUILD_WEBVIEW
-CHROMIUM_WEBVIEW_DIR := $(call my-dir)
-include $(CHROMIUM_WEBVIEW_DIR)/GypAndroid.mk
-include $(CHROMIUM_WEBVIEW_DIR)/android_webview/Android.mk
+CHROMIUM_DIR := $(call my-dir)
+
+# Assume that if the gyp autogenerated makefile exists, we are doing the
+# WebView build.

[joth, 2012/10/24 20:09:58]

nit: the WebView build is a bit ambiguous. (we should standardize terminology)

"we are doing an in android tree build" or  "as part of the android system
build" ?

[Torne, 2012/10/25 11:12:02]

Changed this to "we are doing the WebView build using the Android build system."

+ifneq (,$(wildcard $(CHROMIUM_DIR)/GypAndroid.mk))
+include $(CHROMIUM_DIR)/GypAndroid.mk
+include $(CHROMIUM_DIR)/android_webview/Android.mk
 endif