Fix global dumps to be dumped only when shared memory is actually used

cc/raster/staging_buffer_pool.cc

Index: cc/raster/staging_buffer_pool.cc
diff --git a/cc/raster/staging_buffer_pool.cc b/cc/raster/staging_buffer_pool.cc
index 3cb4b14dfe6da1bc99c0e6ecd259413f1c281a51..66fb9dd895b131c6f53f0e7396b70a73b21448c5 100644
--- a/cc/raster/staging_buffer_pool.cc
+++ b/cc/raster/staging_buffer_pool.cc
@@ -118,8 +118,9 @@ void StagingBuffer::OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd,
       gpu_memory_buffer->GetGUIDForTracing(tracing_process_id);
   pmd->CreateSharedGlobalAllocatorDump(shared_buffer_guid);
 
-  // By creating an edge with a higher |importance| (w.r.t. browser-side dumps)
-  // the tracing UI will account the effective size of the buffer to the child.
+  // By creating an edge with a higher |importance| (w.r.t. browser-side
+  // dumps). the tracing UI will account the effective size of the buffer to
+  // the child.
   const int kImportance = 2;
   pmd->AddOwnershipEdge(buffer_dump->guid(), shared_buffer_guid, kImportance);
 }