Initiate screen context request.

Screen context requests are initiated and sent to the server when:
- UI is shown (when not using stylus input modality).
- Metalayer session is complete (when using stylus input modality).

Still TODO:
- Initially inactivate widget and activate after request callback runs.
- Cache/show server response.

Bug: b:111008970
Change-Id: Ibc2934be60bccc62e63a523384c2739a4ecfdabd
Reviewed-on: https://chromium-review.googlesource.com/1129390
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573446}

ash/assistant/assistant_controller.cc

@@ -118,12 +118,13 @@ AssistantController::AssistantController()
   assistant_ui_controller_->SetAssistantInteractionController(
       assistant_interaction_controller_.get());
 
-  // Observe HighlighterController for region selections.
+  assistant_ui_controller_->AddModelObserver(this);
   Shell::Get()->highlighter_controller()->AddObserver(this);
 }
 
 AssistantController::~AssistantController() {
   Shell::Get()->highlighter_controller()->RemoveObserver(this);
+  assistant_ui_controller_->RemoveModelObserver(this);
 
   // Explicitly clean up the circular dependency in the sub-controllers.
   assistant_interaction_controller_->SetAssistantUiController(nullptr);
@@ -256,10 +257,27 @@ void AssistantController::DownloadImage(
   assistant_image_downloader_->Download(account_id, url, std::move(callback));
 }
 
+void AssistantController::OnUiVisibilityChanged(bool visible,
+                                                AssistantSource source) {
+  // We don't initiate a contextual query for caching if the UI is being hidden.
+  if (!visible)
+    return;
+
+  // We don't initiate a contextual query for caching if we are using stylus
+  // input modality because we will do so on metalayer session complete.
+  if (assistant_interaction_controller_->model()->input_modality() ==
+      InputModality::kStylus) {
+    return;
+  }
+
+  // TODO(dmblack): Activate the Assistant UI when the callback is run.
+  assistant_->RequestScreenContext(gfx::Rect(), base::DoNothing());
+}
+
 void AssistantController::OnHighlighterSelectionRecognized(
     const gfx::Rect& rect) {
-  // TODO(muyuanli): Request screen context for |rect|.
-  NOTIMPLEMENTED();
+  // TODO(dmblack): Activate the Assistant UI when the callback is run.
+  assistant_->RequestScreenContext(rect, base::DoNothing());
 }
 
 void AssistantController::OnOpenUrlFromTab(const GURL& url) {

ash/assistant/assistant_controller.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "ash/ash_export.h"
+#include "ash/assistant/model/assistant_ui_model_observer.h"
 #include "ash/highlighter/highlighter_controller.h"
 #include "ash/public/interfaces/assistant_controller.mojom.h"
 #include "ash/public/interfaces/assistant_image_downloader.mojom.h"
@@ -37,6 +38,7 @@ class AssistantUiController;
 
 class ASH_EXPORT AssistantController
     : public mojom::AssistantController,
+      public AssistantUiModelObserver,
       public HighlighterController::Observer,
       public mojom::ManagedWebContentsOpenUrlDelegate {
  public:
@@ -85,6 +87,9 @@ class ASH_EXPORT AssistantController
   void RequestScreenshot(const gfx::Rect& rect,
                          RequestScreenshotCallback callback) override;
 
+  // AssistantUiModelObserver:
+  void OnUiVisibilityChanged(bool visible, AssistantSource source) override;
+
   // HighlighterController::Observer:
   void OnHighlighterSelectionRecognized(const gfx::Rect& rect) override;
 

ash/assistant/assistant_ui_controller.cc

@@ -199,6 +199,8 @@ void AssistantUiController::ShowUi(AssistantSource source) {
     container_view_->GetWidget()->AddObserver(this);
   }
 
+  // TODO(dmblack): Initially show UI as inactive and only activate after the
+  // screen context has been sent to the server.
   container_view_->GetWidget()->Show();
   assistant_ui_model_.SetVisible(true, source);
 }

chromeos/services/assistant/assistant_manager_service_impl.cc

@@ -178,15 +178,17 @@ void AssistantManagerServiceImpl::RequestScreenContext(
     return;
   }
 
+  // We wait for the closure to execute twice: once for the screenshot and once
+  // for the view hierarchy.
   auto on_done = base::BarrierClosure(
-      2,  // We wait for the closure execute twice: 1 for screenshot and 1 for
-          // view hierarchy.
-      base::BindOnce(
-          &AssistantManagerServiceImpl::SendContextQueryAndRunCallback,
-          weak_factory_.GetWeakPtr(), std::move(callback)));
+      2, base::BindOnce(
+             &AssistantManagerServiceImpl::SendContextQueryAndRunCallback,
+             weak_factory_.GetWeakPtr(), std::move(callback)));
+
   service_->client()->RequestAssistantStructure(
       base::BindOnce(&AssistantManagerServiceImpl::OnAssistantStructureReceived,
                      weak_factory_.GetWeakPtr(), on_done));
+
   // TODO(muyuanli): handle metalayer and grab only part of the screen.
   service_->assistant_controller()->RequestScreenshot(
       region, base::BindOnce(