Adding build-time option to enable the tracing of skia events in

skia/config/SkUserConfig.h

 /*
  * Copyright (C) 2006 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
@@ skipping 138 matching lines @@
 
 
 /*  If SK_DEBUG is defined, then you can optionally define SK_SUPPORT_UNITTEST
     which will run additional self-tests at startup. These can take a long time,
     so this flag is optional.
  */
 #ifdef SK_DEBUG
 #define SK_SUPPORT_UNITTEST
 #endif
 
+/* If your system embeds skia and has complex event logging, define this
+   symbol to name a file that maps the following macros to your system's
+   equivalents:
+       SK_TRACE_EVENT0(event)
+       SK_TRACE_EVENT1(event, name1, value1)
+       SK_TRACE_EVENT2(event, name1, value1, name2, value2)
+   src/utils/SkDebugTrace.h has a trivial implementation that writes to
+   the debug output stream. If SK_USER_TRACE_INCLUDE_FILE is not defined,
+   SkTrace.h will define the above three macros to do nothing.
+*/
+#undef SK_USER_TRACE_INCLUDE_FILE
+
 /* If this is not defined, skia dithers gradients. Turning this on will make
    gradients look better, but might have a performance impact. When it's turned
    on, several webkit pixel tests will need to be rebaselined, too.
    http://crbug.com/41756
  */
 #define SK_DISABLE_DITHER_32BIT_GRADIENT
 
 // ===== Begin Chrome-specific definitions =====
 
 #define SK_SCALAR_IS_FLOAT
@@ skipping 61 matching lines @@
 #error Read the comment at this location
 #endif
 
 #endif
 
 // The default crash macro writes to badbeef which can cause some strange
 // problems. Instead, pipe this through to the logging function as a fatal
 // assertion.
 #define SK_CRASH() SkDebugf_FileLine(__FILE__, __LINE__, true, "SK_CRASH")
 
+// Uncomment the following line to forward skia trace events to Chrome
+// tracing.
+// #define SK_USER_TRACE_INCLUDE_FILE "skia/ext/skia_trace_shim.h"
+
 // ===== End Chrome-specific definitions =====
 
 #endif