gfx: Use unsigned strides for gpu memory buffers.

cc/test/test_gpu_memory_buffer_manager.cc

Index: cc/test/test_gpu_memory_buffer_manager.cc
diff --git a/cc/test/test_gpu_memory_buffer_manager.cc b/cc/test/test_gpu_memory_buffer_manager.cc
index fdf073e56ff4da02a855312541f28c1472a2e976..a947c474937e25c184d187cfef5c34288dc3d4b2 100644
--- a/cc/test/test_gpu_memory_buffer_manager.cc
+++ b/cc/test/test_gpu_memory_buffer_manager.cc
@@ -59,9 +59,9 @@ class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
   }
   gfx::Size GetSize() const override { return size_; }
   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)));
   }
   gfx::GpuMemoryBufferId GetId() const override { return id_; }
@@ -70,7 +70,7 @@ 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;
   }
   ClientBuffer AsClientBuffer() override {
@@ -106,7 +106,7 @@ class GpuMemoryBufferFromClient : public gfx::GpuMemoryBuffer {
   gfx::BufferFormat GetFormat() const override {
     return client_buffer_->GetFormat();
   }
-  int stride(size_t plane) const override {
+  uint32_t stride(size_t plane) const override {
     return client_buffer_->stride(plane);
   }
   gfx::GpuMemoryBufferId GetId() const override { return id_; }