Add importorder to Java styleguide.

styleguide/java/java.md

Index: styleguide/java/java.md
diff --git a/styleguide/java/java.md b/styleguide/java/java.md
index 0567689a48e2e17ed172a2c3e2f9263c9a4fceea..76d5f753353b8d98095236421e3d328fbba06aac 100644
--- a/styleguide/java/java.md
+++ b/styleguide/java/java.md
@@ -124,6 +124,27 @@ if (org.chromium.base.BuildConfig.DCHECK_IS_ON) {
 }
 ```
 
+### Import Order
+
+* Static imports go before other imports.
+* Each import group must be separated by an empty line.
+
+This is the order of the import groups:
+
+1. android
+1. com (except com.google.android.apps.chrome)
+1. dalvik
+1. junit
+1. org
+1. com.google.android.apps.chrome
+1. org.chromium
+1. java
+1. javax
+
+This is enforced by the
+[Chromium Checkstyle configuration](../../tools/android/checkstyle/chromium-style-5.0.xml)
+under the ImportOrder module.
+
 ## Location
 
 "Top level directories" are defined as directories with a GN file, such as