assistant: fix metalayer scale and hook up selection region

Bug: None
Test: Manual
Change-Id: I7a9968bb3b421ef26cc90dd68b063e514e3f4094
Reviewed-on: https://chromium-review.googlesource.com/1147502
Commit-Queue: Muyuan Li <muyuanli@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577692}

ash/assistant/assistant_screen_context_controller.cc

@@ -175,9 +175,8 @@ void AssistantScreenContextController::RequestScreenContext(
   assistant_screen_context_model_.SetRequestState(
       ScreenContextRequestState::kInProgress);
 
-  // Request screen context for the entire screen.
   assistant_->RequestScreenContext(
-      gfx::Rect(),
+      rect,
       base::BindOnce(
           &AssistantScreenContextController::OnScreenContextRequestFinished,
           screen_context_request_factory_.GetWeakPtr()));

ash/assistant/assistant_screen_context_controller.h

@@ -50,9 +50,9 @@ class ASH_EXPORT AssistantScreenContextController
   void AddModelObserver(AssistantScreenContextModelObserver* observer);
   void RemoveModelObserver(AssistantScreenContextModelObserver* observer);
 
-  // Requests a screenshot for the region defined by |rect|. If an empty rect is
-  // supplied, the entire screen is captured. Upon screenshot completion, the
-  // specified |callback| is run.
+  // Requests a screenshot for the region defined by |rect| (given in DP). If
+  // an empty rect is supplied, the entire screen is captured. Upon screenshot
+  // completion, the specified |callback| is run.
   void RequestScreenshot(
       const gfx::Rect& rect,
       mojom::AssistantController::RequestScreenshotCallback callback);

ash/highlighter/highlighter_controller.cc

@@ -15,6 +15,7 @@
 #include "ash/shell.h"
 #include "ash/system/palette/palette_utils.h"
 #include "base/metrics/histogram_macros.h"
+#include "chromeos/chromeos_switches.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/base_event_utils.h"
@@ -222,7 +223,16 @@ void HighlighterController::RecognizeGesture() {
 
   if (!box.IsEmpty() &&
       gesture_type != HighlighterGestureType::kNotRecognized) {
-    const gfx::Rect selection_rect = gfx::ToEnclosingRect(
+    // TODO(muyuanli): Delete the check when native assistant is default on.
+    // This is a temporary workaround to support both ARC-based assistant
+    // and native assistant. In ARC-based assistant, we send the rect in pixels
+    // to ARC side, where the app will crop the screenshot. In native assistant,
+    // we pass the rect directly to UI snapshot API, which assumes coordinates
+    // in DP.
+    const gfx::Rect selection_rect =
+        chromeos::switches::IsAssistantEnabled()
+            ? gfx::ToEnclosingRect(box)
+            : gfx::ToEnclosingRect(
                   gfx::ScaleRect(box, GetScreenshotScale(current_window)));
     if (client_)
       client_->HandleSelection(selection_rect);