Revert "Read data from TfLite model file off thread"

This reverts commit 9666a97.

Reason for revert: Causing crashes. See https://bugs.chromium.org/p/chromium/issues/detail?id=1277884

Original change's description:
> Read data from TfLite model file off thread
>
> While classification happens off-thread, the process of reading from
> the model file and passing the model data between threads can still
> impact the main thread.
>
> Since a trivial TfLite model file does not cause any regression in
> Largest Contentful Paint, we speculate that this time is the root
> cause of the regression.
>
> Bug: 1277600
> Change-Id: I4bfe5d21bc3141e5101d449a00ce4549ca1c424e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3321309
> Reviewed-by: Varun Khaneja <vakh@chromium.org>
> Commit-Queue: Daniel Rubery <drubery@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#949141}

Bug: 1277600
Change-Id: Id443ca5aa850c44db1b48d0b12fe34a3b624c000
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3324702
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/main@{#949806}

components/safe_browsing/content/renderer/phishing_classifier/flatbuffer_scorer.cc

@@ -196,7 +196,9 @@ void FlatBufferModelScorer::ApplyVisualTfLiteModel(
         base::BindOnce(&ApplyVisualTfLiteModelHelper, bitmap,
                        flatbuffer_model_->tflite_metadata()->input_width(),
                        flatbuffer_model_->tflite_metadata()->input_height(),
-                       GetWeakPtr()),
+                       std::string(reinterpret_cast<const char*>(
+                                       visual_tflite_model_.data()),
+                                   visual_tflite_model_.length())),
         std::move(callback));
     base::UmaHistogramTimes(
         "SBClientPhishing.TfLiteModelLoadTime.FlatbufferScorer",

components/safe_browsing/content/renderer/phishing_classifier/protobuf_scorer.cc

@@ -161,7 +161,10 @@ void ProtobufModelScorer::ApplyVisualTfLiteModel(
         {base::TaskPriority::BEST_EFFORT, base::WithBaseSyncPrimitives()},
         base::BindOnce(&ApplyVisualTfLiteModelHelper, bitmap,
                        model_.tflite_metadata().input_width(),
-                       model_.tflite_metadata().input_height(), GetWeakPtr()),
+                       model_.tflite_metadata().input_height(),
+                       std::string(reinterpret_cast<const char*>(
+                                       visual_tflite_model_.data()),
+                                   visual_tflite_model_.length())),
         std::move(callback));
     base::UmaHistogramTimes(
         "SBClientPhishing.TfLiteModelLoadTime.ProtobufScorer",

components/safe_browsing/content/renderer/phishing_classifier/scorer.cc

@@ -113,16 +113,10 @@ std::vector<double> Scorer::ApplyVisualTfLiteModelHelper(
     const SkBitmap& bitmap,
     int input_width,
     int input_height,
-    base::WeakPtr<Scorer> scorer) {
-  if (!scorer)
-    return std::vector<double>();
-
+    const std::string& model_data) {
   TRACE_EVENT0("safe_browsing", "ApplyVisualTfLiteModel");
-  std::string model_data = std::string(
-      reinterpret_cast<const char*>(scorer->visual_tflite_model().data()),
-      scorer->visual_tflite_model().length());
   std::unique_ptr<tflite::task::vision::ImageClassifier> classifier =
-      CreateClassifier(std::move(model_data));
+      CreateClassifier(model_data);
   if (!classifier)
     return std::vector<double>();
 
@@ -167,8 +161,4 @@ double Scorer::LogOdds2Prob(double log_odds) {
 Scorer::Scorer() = default;
 Scorer::~Scorer() = default;
 
-base::WeakPtr<Scorer> Scorer::GetWeakPtr() const {
-  return weak_ptr_factory_.GetWeakPtr();
-}
-
 }  // namespace safe_browsing

components/safe_browsing/content/renderer/phishing_classifier/scorer.h

@@ -84,11 +84,6 @@ class Scorer {
   virtual void ApplyVisualTfLiteModel(
       const SkBitmap& bitmap,
       base::OnceCallback<void(std::vector<double>)> callback) const = 0;
-
-  const base::MemoryMappedFile& visual_tflite_model() const {
-    return visual_tflite_model_;
-  }
-
 #endif
 
   // Returns the version number of the loaded client model.
@@ -133,8 +128,6 @@ class Scorer {
   Scorer(const Scorer&) = delete;
   Scorer& operator=(const Scorer&) = delete;
 
-  base::WeakPtr<Scorer> GetWeakPtr() const;
-
  protected:
   // Helper function which converts log odds to a probability in the range
   // [0.0,1.0].
@@ -145,7 +138,7 @@ class Scorer {
       const SkBitmap& bitmap,
       int input_width,
       int input_height,
-      base::WeakPtr<Scorer> scorer);
+      const std::string& model_data);
 
   base::MemoryMappedFile visual_tflite_model_;
   base::WeakPtrFactory<Scorer> weak_ptr_factory_{this};