Convert CreateCdmBuffer() to use size_t for |capacity|

media/cdm/simple_cdm_buffer.cc

Index: media/cdm/simple_cdm_buffer.cc
diff --git a/media/cdm/simple_cdm_buffer.cc b/media/cdm/simple_cdm_buffer.cc
index c5f3b8bbf96d0e88d159cb81d49e299a1ad148f8..6e0074e1ac2e5a3dd80719105c9b0293ac940d57 100644
--- a/media/cdm/simple_cdm_buffer.cc
+++ b/media/cdm/simple_cdm_buffer.cc
@@ -4,14 +4,23 @@
 
 #include "media/cdm/simple_cdm_buffer.h"
 
+#include <limits>
+
 #include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
 
 namespace media {
 
 // static
-SimpleCdmBuffer* SimpleCdmBuffer::Create(uint32_t capacity) {
+SimpleCdmBuffer* SimpleCdmBuffer::Create(size_t capacity) {
   DCHECK(capacity);
-  return new SimpleCdmBuffer(capacity);
+
+  // cdm::Buffer interface limits capacity to uint32. Requests bigger than
+  // uint32_max will fail.
+  if (capacity > static_cast<size_t>(std::numeric_limits<uint32_t>::max()))
+    return nullptr;

[xhwang, 2016/03/15 06:17:22]

This should really never happen since the caller only uses uint32. A DCHECK here
plus the checked_cast below seem sufficient.

[jrummell, 2016/03/15 18:49:42]

Done.

+
+  return new SimpleCdmBuffer(base::checked_cast<uint32_t>(capacity));
 }
 
 SimpleCdmBuffer::SimpleCdmBuffer(uint32_t capacity)