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

cc/raster/staging_buffer_pool.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/raster/staging_buffer_pool.h"
 
 #include <memory>
 
 #include "base/memory/memory_coordinator_client_registry.h"
 #include "base/memory/ptr_util.h"
@@ skipping 100 matching lines @@
                          in_free_list ? buffer_size_in_bytes : 0);
 
   // Emit an ownership edge towards a global allocator dump node.
   const uint64_t tracing_process_id =
       base::trace_event::MemoryDumpManager::GetInstance()
           ->GetTracingProcessId();
   auto shared_buffer_guid =
       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);
 }
 
 StagingBufferPool::StagingBufferPool(base::SequencedTaskRunner* task_runner,
                                      ContextProvider* worker_context_provider,
                                      ResourceProvider* resource_provider,
                                      bool use_partial_raster,
                                      int max_staging_buffer_usage_in_bytes)
     : task_runner_(task_runner),
@@ skipping 300 matching lines @@
   }
 }
 
 void StagingBufferPool::OnPurgeMemory() {
   base::AutoLock lock(lock_);
   // Release all buffers, regardless of how recently they were used.
   ReleaseBuffersNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
 }
 
 }  // namespace cc