Uses SNPRINT macro where possible. Otherwise uses #define for format.

runtime/vm/os_android.cc

Index: runtime/vm/os_android.cc
diff --git a/runtime/vm/os_android.cc b/runtime/vm/os_android.cc
index 676e2780a7058f5fa7b1559a1c7b11ba1dc02ec4..ddcc45fc4a842259e796913efe116324a8afafda 100644
--- a/runtime/vm/os_android.cc
+++ b/runtime/vm/os_android.cc
@@ -44,12 +44,11 @@ class PerfCodeObserver : public CodeObserver {
     if (file_open == NULL) {
       return;
     }
-    const char* format = "/tmp/perf-%ld.map";
     intptr_t pid = getpid();
-    intptr_t len = OS::SNPrint(NULL, 0, format, pid);
-    char* filename = new char[len + 1];
-    OS::SNPrint(filename, len + 1, format, pid);
+    char* filename = NULL;
+    SNPRINT(filename, malloc, "/tmp/perf-%ld.map", pid);
     out_file_ = (*file_open)(filename, true);
+    free(filename);
   }
 
   ~PerfCodeObserver() {
@@ -73,12 +72,11 @@ class PerfCodeObserver : public CodeObserver {
     if ((file_write == NULL) || (out_file_ == NULL)) {
       return;
     }
-    const char* format = "%" Px " %" Px " %s%s\n";
     const char* marker = optimized ? "*" : "";
-    intptr_t len = OS::SNPrint(NULL, 0, format, base, size, marker, name);
-    char* buffer = Thread::Current()->zone()->Alloc<char>(len + 1);
-    OS::SNPrint(buffer, len + 1, format, base, size, marker, name);
-    (*file_write)(buffer, len, out_file_);
+    char* buffer = NULL;
+    SNPRINT(buffer, Thread::Current()->zone()->Alloc<char>,
+            "%" Px " %" Px " %s%s\n", base, size, marker, name);
+    (*file_write)(buffer, strlen(buffer), out_file_);
   }
 
  private:
@@ -107,10 +105,9 @@ class GdbCodeObserver : public CodeObserver {
       // the prologue sequence is not the first instruction:
       // <name>_entry is used for code preceding the prologue sequence.
       // <name> for rest of the code (first instruction is prologue sequence).
-      const char* kFormat = "%s_%s";
-      intptr_t len = OS::SNPrint(NULL, 0, kFormat, name, "entry");
-      char* pname = Thread::Current()->zone()->Alloc<char>(len + 1);
-      OS::SNPrint(pname, (len + 1), kFormat, name, "entry");
+      char* pname = NULL;
+      SNPRINT(pname, Thread::Current()->zone()->Alloc<char>, "%s_%s",
+              name, "entry");
       DebugInfo::RegisterSection(pname, base, size);
       DebugInfo::RegisterSection(name,
                                  (base + prologue_offset),