Initialize GPU shader disk cache on brower thread.

content/browser/gpu/browser_gpu_channel_host_factory.cc

Index: content/browser/gpu/browser_gpu_channel_host_factory.cc
diff --git a/content/browser/gpu/browser_gpu_channel_host_factory.cc b/content/browser/gpu/browser_gpu_channel_host_factory.cc
index 750a8e4365f79e6f16e45ff7ef62a206710cce3d..87f646c3031a01c3b24f5528aa867325a509bfab 100644
--- a/content/browser/gpu/browser_gpu_channel_host_factory.cc
+++ b/content/browser/gpu/browser_gpu_channel_host_factory.cc
@@ -5,6 +5,7 @@
 #include "content/browser/gpu/browser_gpu_channel_host_factory.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/location.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/single_thread_task_runner.h"
@@ -17,11 +18,14 @@
 #include "content/browser/gpu/gpu_data_manager_impl.h"
 #include "content/browser/gpu/gpu_process_host.h"
 #include "content/browser/gpu/gpu_surface_tracker.h"
+#include "content/browser/gpu/shader_disk_cache.h"
 #include "content/common/child_process_host_impl.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/gpu_data_manager.h"
 #include "content/public/common/content_client.h"
+#include "gpu/command_buffer/service/gpu_switches.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/message_filter.h"
 
@@ -144,6 +148,18 @@ void BrowserGpuChannelHostFactory::EstablishRequest::EstablishOnIO() {
     reused_gpu_process_ = true;
   }
 
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableGpuShaderDiskCache)) {
+    base::FilePath user_data_dir =
+        GetContentClient()->browser()->GetUserDataDirectory();
+    if (!user_data_dir.empty()) {
+      ShaderCacheFactory::GetInstance()->SetCacheInfo(gpu_client_id_,
+                                                      user_data_dir);

[Ken Russell (switch to Gerrit), 2015/08/06 01:01:01]

Something seems suspicious about this. GpuChannels mostly map 1:1 to renderer
processes. This is going to be called once per each renderer process that
attempts to communicate with the GPU process, which seems wrong.
RenderProcessHostImpl::RenderProcessHostImpl already sets up the shader cache
for every spawned renderer.

As far as I understand the problem, the GpuChannels that the browser compositor
creates are the ones that don't have the shader disk cache set up properly. I
think we need to track down the code path that initializes those GpuChannels
specifically.

[piman, 2015/08/06 19:53:13]

FYI, this code path is to setup the GpuChannelHost for the browser - it's the
equivalent of what RenderThreadImpl::EstablishGpuChannelSync does in the
renderer. gpu_client_id_ is the channel id for the browser.

This is going to be called once per GPU process restart though. It seems like an
odd place to put it. Maybe instead you could post a task to the IO thread from
the BrowserGpuChannelHostFactory constructor, only once?

+    } else {
+      LOG(ERROR) << "Failed to init browser shader cache.";
+    }
+  }
+
   host->EstablishGpuChannel(
       gpu_client_id_,
       gpu_client_tracing_id_,