Add method ScheduleTaskOnMainThread() for scheduling tasks.

The Pepper plugin uses pp::Core::CallOnMainThread() to schedule tasks
on the main Pepper thread, while the non-Pepper plugin plans to use
base::SingleThreadTaskRunner() instead in the future.

This CL adds method ScheduleTaskOnMainThread() to PDFEngine::Client and
PaintManager::Client as a wrapper for pp::Core::CallOnMainThread() and
base::SingleThreadTaskRunner() calls, so that direct calls of these two
functions can be removed in the code shared by the Pepper and the
non-Pepper plugin.

Bug: 1108517
Change-Id: Ie1103adce2dbcf40ece40f318f7c3159f67e93ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2594508
Commit-Queue: Hui Yingst <nigi@chromium.org>
Reviewed-by: K. Moon <kmoon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838713}

pdf/out_of_process_instance.cc

@@ -18,6 +18,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/feature_list.h"
+#include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/histogram_functions.h"
@@ -27,6 +28,7 @@
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
 #include "base/values.h"
 #include "build/chromeos_buildflags.h"
 #include "net/base/escape.h"
@@ -243,7 +245,8 @@ constexpr char kJSGetThumbnailHeight[] = "height";
 constexpr char kJSSetReadOnlyType[] = "setReadOnly";
 constexpr char kJSEnableReadOnly[] = "enableReadOnly";
 
-constexpr int kFindResultCooldownMs = 100;
+constexpr base::TimeDelta kFindResultCooldown =
+    base::TimeDelta::FromMilliseconds(100);
 
 // Do not save files with over 100 MB. This cap should be kept in sync with and
 // is also enforced in chrome/browser/resources/pdf/pdf_viewer.js.
@@ -256,7 +259,8 @@ constexpr int kInvalidPDFIndex = -2;
 
 // A delay to wait between each accessibility page to keep the system
 // responsive.
-constexpr int kAccessibilityPageDelayMs = 100;
+constexpr base::TimeDelta kAccessibilityPageDelay =
+    base::TimeDelta::FromMilliseconds(100);
 
 constexpr double kMinZoom = 0.01;
 
@@ -864,11 +868,10 @@ void OutOfProcessInstance::LoadAccessibility() {
   SendAccessibilityViewportInfo();
 
   // Schedule loading the first page.
-  pp::Module::Get()->core()->CallOnMainThread(
-      kAccessibilityPageDelayMs,
-      PPCompletionCallbackFromResultCallback(
-          base::BindOnce(&OutOfProcessInstance::SendNextAccessibilityPage,
-                         weak_factory_.GetWeakPtr())),
+  ScheduleTaskOnMainThread(
+      kAccessibilityPageDelay,
+      base::BindOnce(&OutOfProcessInstance::SendNextAccessibilityPage,
+                     weak_factory_.GetWeakPtr()),
       0);
 }
 
@@ -898,11 +901,10 @@ void OutOfProcessInstance::SendNextAccessibilityPage(int32_t page_index) {
                                     pp_text_runs, pp_chars, page_objects);
 
   // Schedule loading the next page.
-  pp::Module::Get()->core()->CallOnMainThread(
-      kAccessibilityPageDelayMs,
-      PPCompletionCallbackFromResultCallback(
-          base::BindOnce(&OutOfProcessInstance::SendNextAccessibilityPage,
-                         weak_factory_.GetWeakPtr())),
+  ScheduleTaskOnMainThread(
+      kAccessibilityPageDelay,
+      base::BindOnce(&OutOfProcessInstance::SendNextAccessibilityPage,
+                     weak_factory_.GetWeakPtr()),
       page_index + 1);
 }
 
@@ -1324,11 +1326,10 @@ void OutOfProcessInstance::NotifyNumberOfFindResultsChanged(int total,
   NumberOfFindResultsChanged(total, final_result);
   SetTickmarks(tickmarks_);
   recently_sent_find_update_ = true;
-  pp::Module::Get()->core()->CallOnMainThread(
-      kFindResultCooldownMs,
-      PPCompletionCallbackFromResultCallback(
-          base::BindOnce(&OutOfProcessInstance::ResetRecentlySentFindUpdate,
-                         weak_factory_.GetWeakPtr())),
+  ScheduleTaskOnMainThread(
+      kFindResultCooldown,
+      base::BindOnce(&OutOfProcessInstance::ResetRecentlySentFindUpdate,
+                     weak_factory_.GetWeakPtr()),
       0);
 }
 
@@ -1465,9 +1466,10 @@ void OutOfProcessInstance::Print() {
     return;
   }
 
-  pp::Module::Get()->core()->CallOnMainThread(
-      0, PPCompletionCallbackFromResultCallback(base::BindOnce(
-             &OutOfProcessInstance::OnPrint, weak_factory_.GetWeakPtr())));
+  ScheduleTaskOnMainThread(base::TimeDelta(),
+                           base::BindOnce(&OutOfProcessInstance::OnPrint,
+                                          weak_factory_.GetWeakPtr()),
+                           0);
 }
 
 void OutOfProcessInstance::SubmitForm(const std::string& url,
@@ -2284,13 +2286,26 @@ void OutOfProcessInstance::OnPaint(const std::vector<gfx::Rect>& paint_rects,
   engine()->PostPaint();
 
   if (!deferred_invalidates_.empty()) {
-    pp::Module::Get()->core()->CallOnMainThread(
-        0, PPCompletionCallbackFromResultCallback(
-               base::BindOnce(&OutOfProcessInstance::InvalidateAfterPaintDone,
-                              weak_factory_.GetWeakPtr())));
+    ScheduleTaskOnMainThread(
+        base::TimeDelta(),
+        base::BindOnce(&OutOfProcessInstance::InvalidateAfterPaintDone,
+                       weak_factory_.GetWeakPtr()),
+        0);
   }
 }
 
+void OutOfProcessInstance::ScheduleTaskOnMainThread(
+    base::TimeDelta delay,
+    ResultCallback callback,
+    int32_t result,
+    const base::Location& from_here) {
+  int64_t delay_in_msec = delay.InMilliseconds();
+  DCHECK(delay_in_msec <= INT32_MAX);
+  pp::Module::Get()->core()->CallOnMainThread(
+      static_cast<int32_t>(delay_in_msec),
+      PPCompletionCallbackFromResultCallback(std::move(callback)), result);
+}
+
 void OutOfProcessInstance::ProcessPreviewPageInfo(const std::string& url,
                                                   int dest_page_index) {
   DCHECK(IsPrintPreview());

pdf/out_of_process_instance.h

@@ -16,6 +16,7 @@
 
 #include "base/callback.h"
 #include "base/containers/queue.h"
+#include "base/location.h"
 #include "base/memory/weak_ptr.h"
 #include "pdf/pdf_view_plugin_base.h"
 #include "pdf/preview_mode_client.h"
@@ -162,6 +163,11 @@ class OutOfProcessInstance : public PdfViewPluginBase,
   void OnPaint(const std::vector<gfx::Rect>& paint_rects,
                std::vector<PaintReadyRect>* ready,
                std::vector<gfx::Rect>* pending) override;
+  void ScheduleTaskOnMainThread(
+      base::TimeDelta delay,
+      ResultCallback callback,
+      int32_t result,
+      const base::Location& from_here = base::Location::Current()) override;
 
   // PreviewModeClient::Client:
   void PreviewDocumentLoadComplete() override;

pdf/paint_manager.cc

@@ -13,6 +13,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/check.h"
+#include "base/time/time.h"
 #include "pdf/paint_ready_rect.h"
 #include "pdf/ppapi_migration/callback.h"
 #include "pdf/ppapi_migration/geometry_conversions.h"
@@ -161,10 +162,10 @@ void PaintManager::EnsureCallbackPending() {
   if (manual_callback_pending_)
     return;
 
-  pp::Module::Get()->core()->CallOnMainThread(
-      0,
-      PPCompletionCallbackFromResultCallback(base::BindOnce(
-          &PaintManager::OnManualCallbackComplete, weak_factory_.GetWeakPtr())),
+  client_->ScheduleTaskOnMainThread(
+      base::TimeDelta(),
+      base::BindOnce(&PaintManager::OnManualCallbackComplete,
+                     weak_factory_.GetWeakPtr()),
       0);
   manual_callback_pending_ = true;
 }

pdf/paint_manager.h

@@ -10,10 +10,16 @@
 #include <memory>
 #include <vector>
 
+#include "base/location.h"
 #include "base/memory/weak_ptr.h"
 #include "pdf/paint_aggregator.h"
+#include "pdf/ppapi_migration/callback.h"
 #include "ui/gfx/geometry/size.h"
 
+namespace base {
+class TimeDelta;
+}  // namespace base
+
 namespace gfx {
 class Point;
 class Rect;
@@ -66,6 +72,18 @@ class PaintManager {
                          std::vector<PaintReadyRect>* ready,
                          std::vector<gfx::Rect>* pending) = 0;
 
+    // Schedules work to be executed on a main thread after a specific delay.
+    // The `result` parameter will be passed as the argument to the `callback`.
+    // `result` is needed sometimes to emulate calls of some callbacks, but it's
+    // not always needed. `delay` should be no longer than `INT32_MAX`
+    // milliseconds for the Pepper plugin implementation to prevent integer
+    // overflow.
+    virtual void ScheduleTaskOnMainThread(
+        base::TimeDelta delay,
+        ResultCallback callback,
+        int32_t result,
+        const base::Location& from_here = base::Location::Current()) = 0;
+
    protected:
     // You shouldn't be doing deleting through this interface.
     ~Client() = default;

pdf/pdf_engine.h

@@ -13,6 +13,7 @@
 
 #include "base/callback.h"
 #include "base/containers/span.h"
+#include "base/location.h"
 #include "base/optional.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
@@ -20,6 +21,7 @@
 #include "build/build_config.h"
 #include "build/chromeos_buildflags.h"
 #include "pdf/document_layout.h"
+#include "pdf/ppapi_migration/callback.h"
 #include "ppapi/c/dev/pp_cursor_type_dev.h"
 #include "ppapi/c/dev/ppp_printing_dev.h"
 #include "ppapi/cpp/completion_callback.h"
@@ -286,6 +288,18 @@ class PDFEngine {
     // viewers.
     // See https://crbug.com/312882 for an example.
     virtual bool IsValidLink(const std::string& url) = 0;
+
+    // Schedules work to be executed on a main thread after a specific delay.
+    // The `result` parameter will be passed as the argument to the `callback`.
+    // `result` is needed sometimes to emulate calls of some callbacks, but it's
+    // not always needed. `delay` should be no longer than `INT32_MAX`
+    // milliseconds for the Pepper plugin implementation to prevent integer
+    // overflow.
+    virtual void ScheduleTaskOnMainThread(
+        base::TimeDelta delay,
+        ResultCallback callback,
+        int32_t result,
+        const base::Location& from_here = base::Location::Current()) = 0;
   };
 
   struct AccessibilityLinkInfo {

pdf/pdf_view_web_plugin.cc

@@ -12,9 +12,11 @@
 #include <vector>
 
 #include "base/check_op.h"
+#include "base/location.h"
 #include "base/notreached.h"
 #include "base/thread_annotations.h"
 #include "base/threading/thread_checker.h"
+#include "base/time/time.h"
 #include "cc/paint/paint_canvas.h"
 #include "net/cookies/site_for_cookies.h"
 #include "pdf/pdf_engine.h"
@@ -329,6 +331,15 @@ void PdfViewWebPlugin::OnPaint(const std::vector<gfx::Rect>& paint_rects,
   NOTIMPLEMENTED_LOG_ONCE();
 }
 
+void PdfViewWebPlugin::ScheduleTaskOnMainThread(
+    base::TimeDelta delay,
+    ResultCallback callback,
+    int32_t result,
+    const base::Location& from_here) {
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+      from_here, base::BindOnce(std::move(callback), result), delay);
+}
+
 bool PdfViewWebPlugin::IsValid() const {
   return container_ && container_->GetDocument().GetFrame();
 }

pdf/pdf_view_web_plugin.h

@@ -5,6 +5,7 @@
 #ifndef PDF_PDF_VIEW_WEB_PLUGIN_H_
 #define PDF_PDF_VIEW_WEB_PLUGIN_H_
 
+#include "base/location.h"
 #include "base/memory/weak_ptr.h"
 #include "pdf/pdf_view_plugin_base.h"
 #include "pdf/ppapi_migration/url_loader.h"
@@ -108,6 +109,11 @@ class PdfViewWebPlugin final : public PdfViewPluginBase,
   void OnPaint(const std::vector<gfx::Rect>& paint_rects,
                std::vector<PaintReadyRect>* ready,
                std::vector<gfx::Rect>* pending) override;
+  void ScheduleTaskOnMainThread(
+      base::TimeDelta delay,
+      ResultCallback callback,
+      int32_t result,
+      const base::Location& from_here = base::Location::Current()) override;
 
   // BlinkUrlLoader::Client:
   bool IsValid() const override;

pdf/pdfium/pdfium_engine.cc

@@ -26,6 +26,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
 #include "build/build_config.h"
 #include "gin/array_buffer.h"
 #include "gin/public/gin_embedders.h"
@@ -1745,10 +1746,10 @@ void PDFiumEngine::StartFind(const std::string& text, bool case_sensitive) {
   if (doc_loader_set_for_testing_) {
     ContinueFind(case_sensitive ? 1 : 0);
   } else {
-    pp::Module::Get()->core()->CallOnMainThread(
-        0,
-        PPCompletionCallbackFromResultCallback(base::BindOnce(
-            &PDFiumEngine::ContinueFind, find_weak_factory_.GetWeakPtr())),
+    client_->ScheduleTaskOnMainThread(
+        base::TimeDelta(),
+        base::BindOnce(&PDFiumEngine::ContinueFind,
+                       find_weak_factory_.GetWeakPtr()),
         case_sensitive ? 1 : 0);
   }
 }

pdf/preview_mode_client.cc

@@ -11,7 +11,9 @@
 #include <utility>
 
 #include "base/callback.h"
+#include "base/location.h"
 #include "base/notreached.h"
+#include "base/time/time.h"
 #include "pdf/document_layout.h"
 #include "pdf/ppapi_migration/url_loader.h"
 
@@ -178,4 +180,12 @@ bool PreviewModeClient::IsValidLink(const std::string& url) {
   return false;
 }
 
+void PreviewModeClient::ScheduleTaskOnMainThread(
+    base::TimeDelta delay,
+    ResultCallback callback,
+    int32_t result,
+    const base::Location& from_here) {
+  NOTREACHED();
+}
+
 }  // namespace chrome_pdf

pdf/preview_mode_client.h

@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "base/callback_forward.h"
+#include "base/location.h"
 #include "pdf/pdf_engine.h"
 
 namespace gfx {
@@ -78,6 +79,11 @@ class PreviewModeClient : public PDFEngine::Client {
   void SetSelectedText(const std::string& selected_text) override;
   void SetLinkUnderCursor(const std::string& link_under_cursor) override;
   bool IsValidLink(const std::string& url) override;
+  void ScheduleTaskOnMainThread(
+      base::TimeDelta delay,
+      ResultCallback callback,
+      int32_t result,
+      const base::Location& from_here = base::Location::Current()) override;
 
  private:
   Client* const client_;

pdf/test/test_client.cc

@@ -6,6 +6,8 @@
 
 #include <memory>
 
+#include "base/location.h"
+#include "base/time/time.h"
 #include "pdf/document_layout.h"
 #include "pdf/ppapi_migration/url_loader.h"
 
@@ -71,4 +73,9 @@ bool TestClient::IsValidLink(const std::string& url) {
   return !url.empty();
 }
 
+void TestClient::ScheduleTaskOnMainThread(base::TimeDelta delay,
+                                          ResultCallback callback,
+                                          int32_t result,
+                                          const base::Location& from_here) {}
+
 }  // namespace chrome_pdf

pdf/test/test_client.h

@@ -8,6 +8,7 @@
 #include <string>
 #include <vector>
 
+#include "base/location.h"
 #include "pdf/pdf_engine.h"
 
 namespace chrome_pdf {
@@ -41,6 +42,11 @@ class TestClient : public PDFEngine::Client {
   void SetSelectedText(const std::string& selected_text) override;
   void SetLinkUnderCursor(const std::string& link_under_cursor) override;
   bool IsValidLink(const std::string& url) override;
+  void ScheduleTaskOnMainThread(
+      base::TimeDelta delay,
+      ResultCallback callback,
+      int32_t result,
+      const base::Location& from_here = base::Location::Current()) override;
 
  private:
   // Not owned. Expected to dangle briefly, as the engine usually is destroyed