Add a gyp flag to allow removing dependency on ppapi.

 - Introduces a new macro ENABLE_PLUGINS
 - Create a new PluginDelegateHelper interface which is used by RenderViewImpl 


This flag will be used to remove all plugins related code from the Android build.

BUG=162667


Review URL: https://chromiumcodereview.appspot.com/11414180

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171162 0039d316-1c4b-4281-b951-d872f2087c98
26 files changed