Allwo building a WebView APK which doesn't contain any code or assets,
and no resources other than the icon. This APK has a special manifest
tag which will direct the system to provide the missing files from
another "donor" package at runtime that has compatible code (this will
be Monochrome).
To enable this to work, a new APK variable is defined called
"generate_buildconfig_java" so that the BuildConfig.java file can be
omitted from this APK (leaving the generated classes.dex containing
nothing but the AAPT-generated R class for the single icon resource).
The runtime doesn't like having multiple APKs in the classpath which
define the same classes, so we need to omit this BuildConfig to avoid
clashing with Monochrome's.
BUG=664456
Review-Url: https://codereview.chromium.org/2634563002
Cr-Original-Commit-Position: refs/heads/master@{#453911}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: cbafd406aff624f7191f76d64e3c0fcb66b60653
09733f0b66