Added trace query code and wired tracing through BrowserProxy so tests can run traces.

chrome/common/automation_messages_internal.h

Index: chrome/common/automation_messages_internal.h
diff --git a/chrome/common/automation_messages_internal.h b/chrome/common/automation_messages_internal.h
index 55020c6574f69909e8818866a4d8eedd311e615e..3e559e265b253e75249feda19ea8dc07215b3ef1 100644
--- a/chrome/common/automation_messages_internal.h
+++ b/chrome/common/automation_messages_internal.h
@@ -1476,6 +1476,22 @@ IPC_SYNC_MESSAGE_CONTROL1_2(AutomationMsg_IsBrowserInApplicationMode,
                             bool /* is_application */,
                             bool /* success */)
 
+// Begin tracing.
+IPC_SYNC_MESSAGE_CONTROL2_1(AutomationMsg_BeginTracing,
+                            std::vector<std::string> /* included_categories */,
+                            std::vector<std::string> /* excluded_categories */,
+                            bool /* success */)
+
+// End tracing (called after BeginTracing).
+IPC_SYNC_MESSAGE_CONTROL0_1(AutomationMsg_EndTracing,
+                            bool /* success */)
+
+// End tracing (called after BeginTracing). Must keep calling until
+// remaining_chunks is 0, because IPC sends fail if the payload is too big.
+IPC_SYNC_MESSAGE_CONTROL0_2(AutomationMsg_GetTracingOutput,
+                            std::string /* json_chunk */,
+                            int /* remaining_chunks */)
+
 // Renderer -> browser messages.
 
 // Sent when the renderer has scheduled a client redirect to occur.