By default the dev build chrome not enable to load the pepper flash plugin automatically.
If dev want to their build chrome load the pepper flash plugin just like the formal release build does,
they need to :
1. change the $\chromiumtrunk\src\third_party\adobe\flash\flapper_version.h then build the chrome
add this two line into the header file, the version number depends on the binary file you got.
#define FLAPPER_AVAILABLE
#define FLAPPER_VERSION_STRING "xx.x.xx.xxx"
2. copy corresponding binary files into the build output folder. Both ${build output folder}\PepperFlashpepflashplayer.dll and ${build output folder}\PepperFlashmanifest.json.
3. run the dev build chrome, double click or from the command line :${build output folder}>chrome.exe[without add the command line switch --ppapi-flash-path]
4. the pepper flash plugin loaded :)