Revert "Remove kLogPluginMessages flag as part of flag cleanup."

content/common/gpu/gpu_channel.cc

Index: content/common/gpu/gpu_channel.cc
diff --git a/content/common/gpu/gpu_channel.cc b/content/common/gpu/gpu_channel.cc
index 3f123e17d7011209750f9dd2dad54290551d1156..75a18e92c9cb8a2c727cac16f1a332596a7d3e7a 100644
--- a/content/common/gpu/gpu_channel.cc
+++ b/content/common/gpu/gpu_channel.cc
@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/string_util.h"
@@ -20,6 +21,7 @@
 #include "content/common/gpu/gpu_channel_manager.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/gpu/sync_point_manager.h"
+#include "content/public/common/content_switches.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/command_buffer/service/gpu_scheduler.h"
 #include "gpu/command_buffer/service/image_manager.h"
@@ -405,6 +407,8 @@ GpuChannel::GpuChannel(GpuChannelManager* gpu_channel_manager,
   DCHECK(client_id);
 
   channel_id_ = IPC::Channel::GenerateVerifiedChannelID("gpu");
+  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  log_messages_ = command_line->HasSwitch(switches::kLogPluginMessages);
 }
 
 
@@ -449,6 +453,11 @@ int GpuChannel::TakeRendererFileDescriptor() {
 #endif  // defined(OS_POSIX)
 
 bool GpuChannel::OnMessageReceived(const IPC::Message& message) {
+  if (log_messages_) {
+    DVLOG(1) << "received message @" << &message << " on channel @" << this
+             << " with type " << message.type();
+  }
+
   if (message.type() == GpuCommandBufferMsg_WaitForTokenInRange::ID ||
       message.type() == GpuCommandBufferMsg_WaitForGetOffsetInRange::ID) {
     // Move Wait commands to the head of the queue, so the renderer
@@ -471,6 +480,10 @@ bool GpuChannel::Send(IPC::Message* message) {
   // The GPU process must never send a synchronous IPC message to the renderer
   // process. This could result in deadlock.
   DCHECK(!message->is_sync());
+  if (log_messages_) {
+    DVLOG(1) << "sending message @" << message << " on channel @" << this
+             << " with type " << message->type();
+  }
 
   if (!channel_) {
     delete message;