Add lightspeed experiments to disable gpu.

chrome/browser/chrome_browser_field_trials_desktop.cc

Index: chrome/browser/chrome_browser_field_trials_desktop.cc
diff --git a/chrome/browser/chrome_browser_field_trials_desktop.cc b/chrome/browser/chrome_browser_field_trials_desktop.cc
index 9f3c516fb87e0d1f133037734df1da04d4eaa047..8f9566b06724a97f6afd46606a3f665a38dedb87 100644
--- a/chrome/browser/chrome_browser_field_trials_desktop.cc
+++ b/chrome/browser/chrome_browser_field_trials_desktop.cc
@@ -20,6 +20,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/common/variations/variations_util.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/common/content_constants.h"
 #include "net/spdy/spdy_session.h"
 #include "ui/base/layout.h"
@@ -63,6 +64,15 @@ void DisableShowProfileSwitcherTrialIfNecessary() {
     trial->Disable();
 }
 
+void SetupLightSpeedTrials() {
+  std::map<std::string, std::string> params;
+  if (!variations::GetVariationParams("LightSpeed", &params))

[gab, 2015/03/10 19:42:12]

Why not use typical GetVariationParamValue("LightSpeed", "NoGpu")?

[Alexei Svitkine (slow), 2015/03/10 19:48:36]

This was setting up up multiple parameters in a previous patchset. If we will
end up adding more things here, it will be a smaller diff. (There are no
efficiency gains since GetVariationParamValue() does a copy of the map
internally anyway.)

[Alexei Svitkine (slow), 2015/03/11 15:57:08]

Done.

+    return;
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();

[gab, 2015/03/10 19:42:12]

Inline this below.

[Alexei Svitkine (slow), 2015/03/11 15:57:08]

Done.

+  if (ContainsKey(params, "NoGpu"))
+    command_line->AppendSwitch(switches::kDisableGpu);
+}
+
 }  // namespace
 
 void SetupDesktopFieldTrials(const base::CommandLine& parsed_command_line,
@@ -71,6 +81,7 @@ void SetupDesktopFieldTrials(const base::CommandLine& parsed_command_line,
   AutoLaunchChromeFieldTrial();
   SetupInfiniteCacheFieldTrial();
   DisableShowProfileSwitcherTrialIfNecessary();
+  SetupLightSpeedTrials();
   SetupShowAppLauncherPromoFieldTrial(local_state);
 }