title: Error on first run of gclient sync --force on Ubuntu
body: <p>After installing all the required software in correct order on Ubuntu, I ran the following 2 commands</p>
  
  <pre><code>$ gclient config http://webrtc.googlecode.com/svn/trunk
  $ gclient sync --force
  </code></pre>
  
  <p>Latter one took some time and downloaded trunk and chromium_deps folders, however, it gave the following errors</p>
  
  <pre><code>________ running '/usr/bin/python trunk/build/gyp_chromium --depth=trunk trunk/all.gyp -Dextra_gyp_flag=0' in '/home/sojharo/Data/server'
  Updating projects from gyp files...
  Traceback (most recent call last):
    File "&lt;string&gt;", line 1, in &lt;module&gt;
  AssertionError: Point $JAVA_HOME or the java_home gyp variable to a directory containing include/jni.h!
  gyp: Call to 'python -c "import os; dir=os.getenv('JAVA_HOME', '/usr/lib/jvm/java-6-sun'); assert os.path.exists(os.path.join(dir, 'include/jni.h')), 'Point \$JAVA_HOME or the java_home gyp variable to a directory containing include/jni.h!'; print dir"' returned exit status 1. while trying to load trunk/all.gyp
  Error: Command /usr/bin/python trunk/build/gyp_chromium --depth=trunk trunk/all.gyp -Dextra_gyp_flag=0 returned non-zero exit status 1 in /home/sojharo/Data/server
  </code></pre>
  
  <p>Please help!</p>