gpu: Reduce direct use of BrowserGpuMemoryBufferManager

content/browser/gpu/browser_gpu_memory_buffer_manager.cc

Index: content/browser/gpu/browser_gpu_memory_buffer_manager.cc
diff --git a/content/browser/gpu/browser_gpu_memory_buffer_manager.cc b/content/browser/gpu/browser_gpu_memory_buffer_manager.cc
index 93310633ae2c0fe5da07cbe272140910ac0178e1..404ea86476b3a4cb1b521efaaaef01ffc73e0507 100644
--- a/content/browser/gpu/browser_gpu_memory_buffer_manager.cc
+++ b/content/browser/gpu/browser_gpu_memory_buffer_manager.cc
@@ -12,6 +12,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/process_memory_dump.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
@@ -71,6 +72,13 @@ BrowserGpuMemoryBufferManager::BrowserGpuMemoryBufferManager(
       gpu_client_tracing_id_(gpu_client_tracing_id) {
   DCHECK(!g_gpu_memory_buffer_manager);
   g_gpu_memory_buffer_manager = this;
+
+  // Enable the dump provider with IO thread affinity. Note that
+  // unregistration happens on the IO thread (See
+  // BrowserProcessSubThread::IOThreadPreCleanUp).
+  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
+      this, "BrowserGpuMemoryBufferManager",
+      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO));

[piman, 2017/07/07 03:57:10]

I don't think the IO thread exists yet at this point

[sadrul, 2017/07/08 03:19:33]

BrowserGpuMemoryBufferManager is created from
BrowserMainLoop::BrowserThreadsStarted() (through BrowserGpuChannelHostFactory)
[1], which happens after all the threads have been created [2].

I have added a DCHECK() here to make sure that continues to be the case.

[1]
https://cs.chromium.org/chromium/src/content/browser/browser_main_loop.cc?l=1450
[2]
https://cs.chromium.org/chromium/src/content/browser/browser_main_loop.cc?l=906

 }
 
 BrowserGpuMemoryBufferManager::~BrowserGpuMemoryBufferManager() {