Fix sign/unsigned warnings in benchmain.cpp and gmmain.cpp



git-svn-id: http://skia.googlecode.com/svn/trunk@8079 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/gmmain.cpp b/gm/gmmain.cpp
index 160a983..0dbf044 100644
--- a/gm/gmmain.cpp
+++ b/gm/gmmain.cpp
@@ -1181,7 +1181,7 @@
 
 #if SK_SUPPORT_GPU
     struct {
-        size_t  fBytes;
+        int     fBytes;
         int     fCount;
     } gpuCacheSize = { -1, -1 }; // -1s mean use the default
 #endif
@@ -1523,7 +1523,7 @@
                     int count;
                     gr->getTextureCacheLimits(&count, &bytes);
                     if (-1 != gpuCacheSize.fBytes) {
-                        bytes = gpuCacheSize.fBytes;
+                        bytes = static_cast<size_t>(gpuCacheSize.fBytes);
                     }
                     if (-1 != gpuCacheSize.fCount) {
                         count = gpuCacheSize.fCount;