[wasm] Add uma stat for asm.js module size

BUG=chromium:770618
R=kschimpf@chromium.org,bradnelson@chromium.org,isherman@chromium.org

Change-Id: I953c9e7b58de0ca9ac05a9f5f64f139fcf7dd1a7
Reviewed-on: https://chromium-review.googlesource.com/703890Reviewed-by: Aseem Garg <aseemgarg@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Commit-Queue: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48353}

src/asmjs/asm-js.cc

@@ -267,6 +267,10 @@ CompilationJob::Status AsmJsCompilationJob::ExecuteJobImpl() {
       ->asm_wasm_translation_peak_memory_bytes()
       ->AddSample(static_cast<int>(translate_zone_size));
   translate_time_ = translate_timer.Elapsed().InMillisecondsF();
+  int module_size = compilation_info()->literal()->end_position() -
+                    compilation_info()->literal()->start_position();
+  compilation_info()->isolate()->counters()->asm_module_size_bytes()->AddSample(
+      module_size);
   if (FLAG_trace_asm_parser) {
     PrintF(
         "[asm.js translation successful: time=%0.3fms, "

src/counters.h

@@ -1028,7 +1028,8 @@ class RuntimeCallTimerScope {
   HR(asm_wasm_translation_peak_memory_bytes,                                  \
      V8.AsmWasmTranslationPeakMemoryBytes, 1, GB, 51)                         \
   HR(wasm_compile_function_peak_memory_bytes,                                 \
-     V8.WasmCompileFunctionPeakMemoryBytes, 1, GB, 51)
+     V8.WasmCompileFunctionPeakMemoryBytes, 1, GB, 51)                        \
+  HR(asm_module_size_bytes, V8.AsmModuleSizeBytes, 1, GB, 51)
 
 #define HISTOGRAM_TIMER_LIST(HT)                                               \
   /* Garbage collection timers. */                                             \