Make jar targets remove .class files before compile

Make jar targets remove .class files before compile

Jar targets package all .class files in their output directory into the
final jar. It should only package those that are actually from .java
files in the src directories. Specifically, it should not package .class
files from .java files that used to be in the src directory but are no
longer there. To prevent packaging these stale .class files, clean the
output directory before the compile step.

One side effect is that we will now have to compile all .java files for
a target each time that that target is rebuilt. And in turn, the _java
targets that depend on it will do the same. Locally, when building the
chrome_java target (which includes all the others) after touching a
base_java input (which will then force all the others to rebuild), this
adds ~3 seconds to the build time... i.e. it's only a very minor hit.

BUG=145983
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=154857

[nilesh, 2012-09-04 21:23:15]

On 2012/09/04 21:04:07, cjhopman wrote:

LGTM

[commit-bot: I haz the power, 2012-09-04 21:50:09]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/cjhopman@chromium.org/10914080/1

[commit-bot: I haz the power, 2012-09-04 23:55:40]

Change committed as 154857