Fix hang when a plugin has child windows that are in a different process.  RedrawWindow would synchronously wait for the child window, during which only some messages are pumped.  This leads to reentrancy with our custom paint message.  Avoiding synchronously calling the child windows in the reentrancy fixes the problem.
Fix hang when a plugin has child windows that are in a different process.  RedrawWindow would synchronously wait for the child window, during which only some messages are pumped.  This leads to reentrancy with our custom paint message.  Avoiding synchronously calling the child windows in the reentrancy fixes the problem.

BUG=2242480
Review URL: http://codereview.chromium.org/501014

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@34593 0039d316-1c4b-4281-b951-d872f2087c98

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