Workaround bogus GCC warning
Workaround bogus GCC warning

I had a single parameter IPC message handler, which took an enumeration
parameter.  For some reason, GCC thought it was possible for the enum
value to be used uninitialized:

cc1plus: warnings being treated as errors
/b/slave/sub-rel-linux/build/src/chrome/common/ipc_message_utils.h: In member function 'virtual void RenderWidget::OnMessageReceived(const IPC::Message&)':
/b/slave/sub-rel-linux/build/src/chrome/common/ipc_message_utils.h:1244: warning: 'p.Tuple1<WebKit::WebTextDirection>::a' may be used uninitialized in this function
/b/slave/sub-rel-linux/build/src/chrome/common/ipc_message_utils.h:1244: note: 'p.Tuple1<WebKit::WebTextDirection>::a' was declared here
scons: *** [/b/slave/sub-rel-linux/build/src/sconsbuild/Release/obj/chrome/renderer/render_widget.o] Error 1

I am able to avoid this warning by adding an explicit branch.

BUG=none
TEST=none
TBR=mpcomplete

Review URL: http://codereview.chromium.org/155624

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@20857 0039d316-1c4b-4281-b951-d872f2087c98

yitian134/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium