Add a command-line flag to set GPU rasterization multisampling.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index e17c792ca341b1fa90959bde8edb1b871b4139bd..5ed693e9df050c0065a027ad08b2b020dcfbf346 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1081,6 +1081,12 @@ static void AppendCompositorCommandLineFlags(base::CommandLine* command_line) {
   if (IsGpuRasterizationEnabled())
     command_line->AppendSwitch(switches::kEnableGpuRasterization);
 
+  if (GpuRasterizationMSAASampleCount() > 0) {

[danakj, 2015/01/27 17:59:35]

FWIW You could remove the if() here and the if(HasSwitch) in the
RenderThreadImpl.

[piman, 2015/01/27 18:07:16]

nit: cache the return value of GpuRasterizationMSAASampleCount()? It parses
strings, and we use it twice.

[Stephen White, 2015/01/27 18:11:45]

Done.

+    command_line->AppendSwitchASCII(
+        switches::kGpuRasterizationMSAASampleCount,
+        base::IntToString(GpuRasterizationMSAASampleCount()));
+  }
+
   DCHECK_IMPLIES(IsZeroCopyUploadEnabled(), !IsOneCopyUploadEnabled());
   DCHECK_IMPLIES(IsOneCopyUploadEnabled(), !IsZeroCopyUploadEnabled());
   if (IsZeroCopyUploadEnabled())