Convert CreateCdmBuffer() to use size_t for |capacity|

media/cdm/simple_cdm_allocator.cc

Index: media/cdm/simple_cdm_allocator.cc
diff --git a/media/cdm/simple_cdm_allocator.cc b/media/cdm/simple_cdm_allocator.cc
index 9c3a46b8c1f4ea352111538622171c101d79eeda..2ae4dd890a1a46012c582ba05f670b703781653f 100644
--- a/media/cdm/simple_cdm_allocator.cc
+++ b/media/cdm/simple_cdm_allocator.cc
@@ -58,7 +58,7 @@ SimpleCdmAllocator::~SimpleCdmAllocator() {}
 // Creates a new SimpleCdmBuffer on every request. It does not keep track of
 // the memory allocated, so the caller is responsible for calling Destroy()
 // on the buffer when it is no longer needed.
-cdm::Buffer* SimpleCdmAllocator::CreateCdmBuffer(uint32_t capacity) {
+cdm::Buffer* SimpleCdmAllocator::CreateCdmBuffer(size_t capacity) {
   if (!capacity)
     return nullptr;