VAVEA: Turn VAAPI encoder flag into a kill switch.

content/common/gpu/media/vaapi_video_encode_accelerator.cc

Index: content/common/gpu/media/vaapi_video_encode_accelerator.cc
diff --git a/content/common/gpu/media/vaapi_video_encode_accelerator.cc b/content/common/gpu/media/vaapi_video_encode_accelerator.cc
index 6cfdd9d1faa3ec46d02428d206cceb5bcd97d7d0..c0cf43ee931ccfaae9cf9493b6a76ec99b76b947 100644
--- a/content/common/gpu/media/vaapi_video_encode_accelerator.cc
+++ b/content/common/gpu/media/vaapi_video_encode_accelerator.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
+#include "base/cpu.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/metrics/histogram.h"
 #include "base/numerics/safe_conversions.h"
@@ -109,8 +110,13 @@ std::vector<media::VideoEncodeAccelerator::SupportedProfile>
 VaapiVideoEncodeAccelerator::GetSupportedProfiles() {
   std::vector<SupportedProfile> profiles;
 
+  base::CPU cpu;
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
-  if (!cmd_line->HasSwitch(switches::kEnableVaapiAcceleratedVideoEncode))
+  bool encode_enabled =
+      (!cmd_line->HasSwitch(switches::kDisableVaapiAcceleratedVideoEncode) &&
+       (cpu.vendor_name() == "GenuineIntel") && (cpu.model() == 55));

[piman, 2014/07/07 17:57:47]

You said this was used in the renderer? Does this correctly work with the
sandbox? base::CPU needs to access files.

I'm not excited about pegging the encoder to the CPU type.

Why not keeping the enable flag and pass it from the board definition on the
Chrome OS side?

[Pawel Osciak, 2014/07/08 05:32:42]

Yes, this is in renderer. PreSandboxStartup()
(https://code.google.com/p/chromium/codesearch#chromium/src/chrome/app/chrome_...)
prepopulates /proc/cpuinfo.
Me neither of course, but there is a bug in the driver that says it's available
even if it's not. I'm waiting for a fix from Intel, so this should hopefully be
temporary.
We have quite a few boards that support this and this way feels to me like a
better idea rather than manually curating a board list in command line builder. 

+
+  if (!encode_enabled)
     return profiles;
 
   SupportedProfile profile;