Remove TraceMessageFilter for NACL_LOADER_PROCESS types that do not support tracing.

BUG=95949
TEST=start and stop trace in about:tracing while nacl app is running; verify it does not hang with "Processing trace"

Review URL: http://codereview.chromium.org/8118013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@103823 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 23 insertions, 7 deletions

diff --git a/content/browser/trace_message_filter.cc b/content/browser/trace_message_filter.cc
index fcefc94..6345888 100644
--- a/content/browser/trace_message_filter.cc
+++ b/content/browser/trace_message_filter.cc
@@ -9,6 +9,7 @@
 
 
 TraceMessageFilter::TraceMessageFilter() :
+    has_child_(false),
     is_awaiting_end_ack_(false),
     is_awaiting_bpf_ack_(false) {
 }
@@ -19,21 +20,21 @@ TraceMessageFilter::~TraceMessageFilter() {
 void TraceMessageFilter::OnFilterAdded(IPC::Channel* channel) {
   // Always on IO thread (BrowserMessageFilter guarantee).
   BrowserMessageFilter::OnFilterAdded(channel);
-
-  TraceController::GetInstance()->AddFilter(this);
 }
 
 void TraceMessageFilter::OnChannelClosing() {
   // Always on IO thread (BrowserMessageFilter guarantee).
   BrowserMessageFilter::OnChannelClosing();
 
-  if (is_awaiting_bpf_ack_)
-    OnEndTracingAck(std::vector<std::string>());
+  if (has_child_) {
+    if (is_awaiting_bpf_ack_)
+      OnEndTracingAck(std::vector<std::string>());
 
-  if (is_awaiting_end_ack_)
-    OnTraceBufferPercentFullReply(0.0f);
+    if (is_awaiting_end_ack_)
+      OnTraceBufferPercentFullReply(0.0f);
 
-  TraceController::GetInstance()->RemoveFilter(this);
+    TraceController::GetInstance()->RemoveFilter(this);
+  }
 }
 
 bool TraceMessageFilter::OnMessageReceived(const IPC::Message& message,
@@ -41,6 +42,8 @@ bool TraceMessageFilter::OnMessageReceived(const IPC::Message& message,
   // Always on IO thread (BrowserMessageFilter guarantee).
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP_EX(TraceMessageFilter, message, *message_was_ok)
+    IPC_MESSAGE_HANDLER(ChildProcessHostMsg_ChildSupportsTracing,
+                        OnChildSupportsTracing)
     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_EndTracingAck, OnEndTracingAck)
     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_TraceDataCollected,
                         OnTraceDataCollected)
@@ -75,6 +78,11 @@ void TraceMessageFilter::SendGetTraceBufferPercentFull() {
   Send(new ChildProcessMsg_GetTraceBufferPercentFull);
 }
 
+void TraceMessageFilter::OnChildSupportsTracing() {
+  has_child_ = true;
+  TraceController::GetInstance()->AddFilter(this);
+}
+
 void TraceMessageFilter::OnEndTracingAck(
     const std::vector<std::string>& known_categories) {
   // is_awaiting_end_ack_ should always be true here, but check in case the
diff --git a/content/browser/trace_message_filter.h b/content/browser/trace_message_filter.h
index c2d5d93..8317efd 100644
--- a/content/browser/trace_message_filter.h
+++ b/content/browser/trace_message_filter.h
@@ -33,11 +33,15 @@ class TraceMessageFilter : public BrowserMessageFilter {
 
  private:
   // Message handlers.
+  void OnChildSupportsTracing();
   void OnEndTracingAck(const std::vector<std::string>& known_categories);
   void OnTraceBufferFull();
   void OnTraceBufferPercentFullReply(float percent_full);
   void OnTraceDataCollected(const std::string& data);
 
+  // ChildTraceMessageFilter exists:
+  bool has_child_;
+
   // Awaiting ack for previously sent SendEndTracing
   bool is_awaiting_end_ack_;
   bool is_awaiting_bpf_ack_;
diff --git a/content/common/child_process_messages.h b/content/common/child_process_messages.h
index b1a8b33..e465b59 100644
--- a/content/common/child_process_messages.h
+++ b/content/common/child_process_messages.h
@@ -48,6 +48,9 @@ IPC_MESSAGE_CONTROL0(ChildProcessMsg_DumpHandles)
 
 IPC_MESSAGE_CONTROL0(ChildProcessHostMsg_ShutdownRequest)
 
+// Notify the browser that this child process supports tracing.
+IPC_MESSAGE_CONTROL0(ChildProcessHostMsg_ChildSupportsTracing)
+
 // Reply from child processes acking ChildProcessMsg_TraceChangeStatus(false).
 IPC_MESSAGE_CONTROL1(ChildProcessHostMsg_EndTracingAck,
                      std::vector<std::string> /* known_categories */)
diff --git a/content/common/child_trace_message_filter.cc b/content/common/child_trace_message_filter.cc
index 4a04ac1..2af2ab1 100644
--- a/content/common/child_trace_message_filter.cc
+++ b/content/common/child_trace_message_filter.cc
@@ -23,6 +23,7 @@ void ChildTraceMessageFilter::OnFilterAdded(IPC::Channel* channel) {
       base::Bind(&ChildTraceMessageFilter::OnTraceDataCollected, this));
   base::debug::TraceLog::GetInstance()->SetBufferFullCallback(
       base::Bind(&ChildTraceMessageFilter::OnTraceBufferFull, this));
+  channel_->Send(new ChildProcessHostMsg_ChildSupportsTracing());
 }
 
 void ChildTraceMessageFilter::OnFilterRemoved() {