Add ability to retrieve a thread_name given a thread_id.

The work to add GPU tracing needs the ability to map from a thread_id back
to a thread_name in order to allow us to have the correct display on the
chrome://tracing page.

We want to be able to output our traces without having to post to a thread
to handle the output, and to have the GPU traces differentiated from the
GPU-process which will be doing the tracing calls.

BUG=111509
TEST=Added tests in base_unittests


Review URL: https://chromiumcodereview.appspot.com/11438022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178886 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 9 insertions, 4 deletions

diff --git a/base/debug/trace_event_impl.cc b/base/debug/trace_event_impl.cc
index e85db1d..411da1d 100644
--- a/base/debug/trace_event_impl.cc
+++ b/base/debug/trace_event_impl.cc
@@ -65,7 +65,9 @@ const int g_category_categories_exhausted = 1;
 const int g_category_metadata = 2;
 int g_category_index = 3; // skip initial 3 categories
 
-// The most-recently captured name of the current thread
+// The name of the current thread. This is used to decide if the current
+// thread name has changed. We combine all the seen thread names into the
+// output name for the thread.
 LazyInstance<ThreadLocalPointer<const char> >::Leaky
     g_current_thread_name = LAZY_INSTANCE_INITIALIZER;
 
diff --git a/base/debug/trace_event_unittest.cc b/base/debug/trace_event_unittest.cc
index cf16fa5..c42cc5d 100644
--- a/base/debug/trace_event_unittest.cc
+++ b/base/debug/trace_event_unittest.cc
@@ -79,15 +79,18 @@ class TraceEventTestFixture : public testing::Test {
   }
 
   virtual void SetUp() OVERRIDE {
-    old_thread_name_ = PlatformThread::GetName();
+    const char* name = PlatformThread::GetName();
+    old_thread_name_ = name ? strdup(name) : NULL;
   }
   virtual void TearDown() OVERRIDE {
     if (TraceLog::GetInstance())
       EXPECT_FALSE(TraceLog::GetInstance()->IsEnabled());
-    PlatformThread::SetName(old_thread_name_ ? old_thread_name_  : "");
+    PlatformThread::SetName(old_thread_name_ ? old_thread_name_ : "");
+    free(old_thread_name_);
+    old_thread_name_ = NULL;
   }
 
-  const char* old_thread_name_;
+  char* old_thread_name_;
   ListValue trace_parsed_;
   base::debug::TraceResultBuffer trace_buffer_;
   base::debug::TraceResultBuffer::SimpleOutput json_output_;