[net] Change order of RequestPriority to natural: higher > lower

net/spdy/spdy_http_utils.cc

Index: net/spdy/spdy_http_utils.cc
diff --git a/net/spdy/spdy_http_utils.cc b/net/spdy/spdy_http_utils.cc
index 0a0df47c4658b80e2e962d2f5bcb0a4cb15f6088..4fae7ecf02b15e9b2807693f830a475b4faaa1d7 100644
--- a/net/spdy/spdy_http_utils.cc
+++ b/net/spdy/spdy_http_utils.cc
@@ -128,18 +128,40 @@ void CreateSpdyHeadersFromHttpRequest(const HttpRequestInfo& info,
 SpdyPriority ConvertRequestPriorityToSpdyPriority(
     const RequestPriority priority,
     int protocol_version) {
-  DCHECK(HIGHEST <= priority && priority < NUM_PRIORITIES);
+  DCHECK_GE(priority, MINIMUM_PRIORITY);

[Ryan Hamilton, 2012/04/23 22:51:05]

One minor problem.  The CQ is about to land this CL:

https://chromiumcodereview.appspot.com/10187006/

It re-writes this method, and in particular eliminates the SPDY_PRIORITY_HIGHEST
symbol.  Not a big deal, but just FYI.

[szym, 2012/04/24 00:19:31]

Thanks for the heads up.

+  DCHECK_LT(priority, NUM_PRIORITIES);
   if (protocol_version == 2) {
     switch (priority) {
+      case HIGHEST:
+        return SPDY_PRIORITY_HIGHEST;
+      case MEDIUM:
+        return SPDY_PRIORITY_HIGHEST + 1;
+      case LOW:
+        return SPDY_PRIORITY_HIGHEST + 2;
       case LOWEST:
         return SPDY_PRIORITY_LOWEST - 1;
       case IDLE:
         return SPDY_PRIORITY_LOWEST;
       default:
-        return priority;
+        NOTREACHED();
+        return SpdyPriority();
     }
   } else {
-    return priority;
+    switch (priority) {

[szym, 2012/04/24 00:19:31]

Do you think this switch would be better expressed as: |return
static_cast<SpdyPriority>(HIGHEST - priority)|.

[Ryan Hamilton, 2012/04/24 00:42:11]

Yup, that sounds great.  The SPDY 2 case could be a similar expression, possibly
offset by 1 for IDLE and LOWEST.  (I did the moral equivalent of this in the new
code)

+      case HIGHEST:
+        return SPDY_PRIORITY_HIGHEST;
+      case MEDIUM:
+        return SPDY_PRIORITY_HIGHEST + 1;
+      case LOW:
+        return SPDY_PRIORITY_HIGHEST + 2;
+      case LOWEST:
+        return SPDY_PRIORITY_HIGHEST + 3;
+      case IDLE:
+        return SPDY_PRIORITY_HIGHEST + 4;
+      default:
+        NOTREACHED();
+        return SpdyPriority();
+    }
   }
 }