gfx: Use unsigned strides for gpu memory buffers.

blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc

Index: blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc
diff --git a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc
index b81b94af41889d42413951fc422821fb5729515e..e7701794ebe52d37fd569fa7fa0206a5b1d5ba9d 100644
--- a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc
+++ b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.cc
@@ -63,9 +63,9 @@ class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
 
   gfx::BufferFormat GetFormat() const override { return format_; }
 
-  int stride(size_t plane) const override {
+  uint32_t stride(size_t plane) const override {
     DCHECK_LT(plane, gfx::NumberOfPlanesForBufferFormat(format_));
-    return base::checked_cast<int>(gfx::RowSizeForBufferFormat(
+    return base::checked_cast<uint32_t>(gfx::RowSizeForBufferFormat(
         size_.width(), format_, static_cast<int>(plane)));
   }
 
@@ -78,7 +78,7 @@ class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
     handle.type = gfx::SHARED_MEMORY_BUFFER;
     handle.handle = shared_memory_->handle();
     handle.offset = base::checked_cast<uint32_t>(offset_);
-    handle.stride = base::checked_cast<int32_t>(stride_);
+    handle.stride = base::checked_cast<uint32_t>(stride_);
     return handle;
   }