Let DM run unit tests.

dm/DMTask.cpp

 #include "DMTask.h"
 
 #include "DMTaskRunner.h"
 #include "DMUtil.h"
 #include "SkBitmap.h"
 #include "SkCommandLineFlags.h"
 
 namespace DM {
 
 Task::Task(Reporter* reporter, TaskRunner* taskRunner)
     : fReporter(reporter), fTaskRunner(taskRunner), fDepth(0) {
     fReporter->start();
 }
 
 Task::Task(const Task& parent)
     : INHERITED(parent)
     , fReporter(parent.fReporter)
     , fTaskRunner(parent.fTaskRunner)
     , fDepth(parent.depth()+1) {
     fReporter->start();
 }
 
 Task::~Task() {}
 
 void Task::run() {
     if (!this->shouldSkip()) {
         this->draw();
     }
-    fReporter->finish();
-    fReporter->updateStatusLine();
+    fReporter->finish(this->name());
     delete this;
 }
 
 void Task::spawnChild(Task* task) {
     if (!task->usesGpu()) {
         fTaskRunner->add(task);
     } else {
         SkDEBUGFAIL("Sorry, we can't spawn GPU tasks. :(  See comment in TaskRunner::wait().");
     }
 }
 
-void Task::fail() {
-    fReporter->fail(this->name());
+void Task::fail(const char* msg) {
+    SkString failure(this->name());
+    if (msg) {
+        failure.appendf(": %s", msg);
+    }
+    fReporter->fail(failure);
 }
 
 }  // namespace DM