Browser tests for starting a drag-and-drop out of an OOPIF.

chrome/browser/drag_and_drop_browsertest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 #include <string>
 
+#include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
 #include "base/strings/pattern.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
-#include "content/browser/frame_host/frame_tree.h"
-#include "content/browser/frame_host/frame_tree_node.h"
-#include "content/browser/frame_host/render_frame_host_impl.h"
-#include "content/browser/web_contents/web_contents_impl.h"
+#include "base/threading/sequenced_task_runner_handle.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/interactive_test_utils.h"
+#include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/public/test/content_browser_test_utils.h"
+#include "content/public/test/test_frame_navigation_observer.h"
 #include "content/public/test/test_utils.h"
-#include "content/shell/browser/shell.h"
 #include "net/base/escape.h"
 #include "net/dns/mock_host_resolver.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/aura/client/drag_drop_client.h"
 #include "ui/aura/client/drag_drop_delegate.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/rect.h"
 #include "url/gurl.h"
 
-namespace content {
+namespace chrome {
 
 namespace {
 
 // TODO(lukasza): Support testing on non-Aura platforms (i.e. Android + Mac?).
 //
 // Notes for the TODO above:
 //
 // - Why inject/simulate drag-and-drop events at the aura::Window* level.
 //
 //   - It seems better to inject into UI libraries to cover code *inside* these
 //     libraries.  This might complicate simulation a little bit (i.e. picking
 //     the right aura::Window and/or aura::client::DragDropDelegate to target),
 //     but otherwise important bits of code wouldn't get test coverage (i.e.
 //     directly injecting into RenderViewHost->DragTargetDragEnter seems wrong).
 //
 //   - In theory, we could introduce WebContentsImpl::DragTargetDragEnter (to be
 //     used by all UI platforms - so reused by web_contents_view_android.cc,
 //     web_contents_view_aura.cc, web_drag_dest_mac.mm), but it feels wrong - UI
 //     libraries should already know which widget is the target of the event and
 //     so should be able to talk directly to the right widget (i.e. WebContents
 //     should not be responsible for mapping coordinates to a widget - this is
 //     the job of the UI library).
 //
 // - Unknowns:
 //
 //   - Will this work for WebView and Plugin testing.
-//
-//   - Will this work for simulating dragging from WebContents into outside of
-//     the browser (without leaving OS drag&drop machinery in a weird state).
 
 // Test helper for simulating drag and drop happening in WebContents.
 class DragAndDropSimulator {
  public:
-  explicit DragAndDropSimulator(WebContents* web_contents)
+  explicit DragAndDropSimulator(content::WebContents* web_contents)
       : web_contents_(web_contents) {}
 
   // Simulates notification that |text| was dragged from outside of the browser,
   // into the specified |location| inside |web_contents|.
   // |location| is relative to |web_contents|.
   // Returns true upon success.
   bool SimulateDragEnter(gfx::Point location, const std::string& text) {
     ui::OSExchangeData data;
     data.SetString(base::UTF8ToUTF16(text));
     return SimulateDragEnter(location, data);
@@ skipping 66 matching lines @@
     *out_event_location = root_location;
   }
 
   // These are ui::DropTargetEvent::source_operations_ being sent when manually
   // trying out drag&drop of an image file from Nemo (Ubuntu's file explorer)
   // into a content_shell.
   static constexpr int kDefaultSourceOperations = ui::DragDropTypes::DRAG_MOVE |
                                                   ui::DragDropTypes::DRAG_COPY |
                                                   ui::DragDropTypes::DRAG_LINK;
 
-  WebContents* web_contents_;
+  content::WebContents* web_contents_;
   std::unique_ptr<ui::DropTargetEvent> active_drag_event_;
 
   DISALLOW_COPY_AND_ASSIGN(DragAndDropSimulator);
 };
 
+// Helper for waiting until a drag-and-drop starts (e.g. in response to a
+// mouse-down + mouse-move simulated by the test).
+class DragStartWaiter : public aura::client::DragDropClient {
+ public:
+  // Starts monitoring |web_contents| for a start of a drag-and-drop.
+  // While alive, prevents a real, OS-level drag-and-drop from starting
+  // for this particular |web_contents|.
+  explicit DragStartWaiter(content::WebContents* web_contents)
+      : web_contents_(web_contents),
+        message_loop_runner_(new content::MessageLoopRunner),
+        drag_started_(false) {
+    DCHECK(web_contents_);
+
+    // Intercept calls to the old DragDropClient.
+    gfx::NativeWindow root_window =
+        web_contents_->GetContentNativeView()->GetRootWindow();
+    old_client_ = aura::client::GetDragDropClient(root_window);
+    aura::client::SetDragDropClient(root_window, this);
+  }
+
+  ~DragStartWaiter() override {
+    // Restore the original DragDropClient.
+    gfx::NativeWindow root_window =
+        web_contents_->GetContentNativeView()->GetRootWindow();
+    aura::client::SetDragDropClient(root_window, old_client_);
+  }
+
+  // Waits until we almost report a drag-and-drop start to the OS
+  // (notifying the OS will be prevented to help the test continue
+  // without entering a nested message loop).
+  //
+  // Returns true if drag and drop has indeed started (and in this
+  // case populates |text|, |html| and other parameters with data
+  // that would have been passed to the OS).
+  bool WaitUntilDragStartIsIntercepted(
+      std::string* text,
+      std::string* html,
+      int* operation,
+      gfx::Point* location_inside_web_contents) {
+    message_loop_runner_->Run();
+
+    if (!drag_started_)
+      return false;
+
+    *text = text_;
+    *html = html_;
+    *operation = operation_;
+    *location_inside_web_contents = location_inside_web_contents_;
+    return true;
+  }
+

[ncarter (slow), 2016/11/11 20:56:36]

  // aura::client::DragDropClient:

[Łukasz Anforowicz, 2016/11/14 17:53:22]

Done.

+  int StartDragAndDrop(const ui::OSExchangeData& data,
+                       aura::Window* root_window,
+                       aura::Window* source_window,
+                       const gfx::Point& screen_location,
+                       int operation,
+                       ui::DragDropTypes::DragEventSource source) override {
+    if (!drag_started_) {
+      drag_started_ = true;
+      message_loop_runner_->Quit();
+
+      base::string16 text;
+      if (data.GetString(&text))
+        text_ = base::UTF16ToUTF8(text);
+      else
+        text_ = "<no text>";
+
+      GURL base_url;
+      base::string16 html;
+      if (data.GetHtml(&html, &base_url))
+        html_ = base::UTF16ToUTF8(html);
+      else
+        html_ = "<no html>";
+
+      gfx::Rect bounds =
+          web_contents_->GetContentNativeView()->GetBoundsInScreen();
+      location_inside_web_contents_ =
+          screen_location - gfx::Vector2d(bounds.x(), bounds.y());
+
+      operation_ = operation;
+    }
+
+    // Forwarding to |old_client_| is undesirable, because test cannot control
+    // next steps after a nested drag-and-drop loop is entered at the OS level
+    // (as is the case in Windows, via DoDragDrop).  Instead, in the test we
+    // kind of ignore renderer's request to start drag and drop and never
+    // forward this request to the OS-specific layers.
+    return 0;
+  }
+
+  void DragCancel() override {
+    ADD_FAILURE() << "Unexpected call to DragCancel";
+  }
+
+  bool IsDragDropInProgress() override { return drag_started_; }
+
+ private:
+  content::WebContents* web_contents_;
+  scoped_refptr<content::MessageLoopRunner> message_loop_runner_;
+  aura::client::DragDropClient* old_client_;
+
+  // Data captured during the first intercepted StartDragAndDrop call.
+  bool drag_started_;
+  std::string text_;
+  std::string html_;
+  int operation_;
+  gfx::Point location_inside_web_contents_;
+};
+
 // Helper for waiting for notifications from
 // content/test/data/drag_and_drop/event_monitoring.js
 class DOMDragEventWaiter {
  public:
   explicit DOMDragEventWaiter(const std::string& event_type_to_wait_for,
-                              const ToRenderFrameHost& target)
+                              const content::ToRenderFrameHost& target)
       : target_frame_name_(target.render_frame_host()->GetFrameName()),
         event_type_to_wait_for_(event_type_to_wait_for),
-        dom_message_queue_(
-            WebContents::FromRenderFrameHost(target.render_frame_host())) {}
+        dom_message_queue_(content::WebContents::FromRenderFrameHost(
+            target.render_frame_host())) {}
 
   // Waits until |target| calls reportDragEvent in
-  // content/test/data/drag_and_drop/event_monitoring.js with event_type
+  // chrome/test/data/drag_and_drop/event_monitoring.js with event_type
   // property set to |event_type_to_wait_for|.  (|target| and
   // |event_type_to_wait_for| are passed to the constructor).
   //
   // Returns the event details via |found_event| (in form of a JSON-encoded
-  // object).  See content/test/data/drag_and_drop/event_monitoring.js for keys
+  // object).  See chrome/test/data/drag_and_drop/event_monitoring.js for keys
   // and properties that |found_event| is expected to have.
   //
   // Returns true upon success.  It is okay if |response| is null.
   bool WaitForNextMatchingEvent(std::string* found_event) WARN_UNUSED_RESULT {
     std::string candidate_event;
     bool got_right_event_type = false;
     bool got_right_window_name = false;
     do {
       if (!dom_message_queue_.WaitForMessage(&candidate_event))
         return false;
 
       got_right_event_type = base::MatchPattern(
           candidate_event, base::StringPrintf("*\"event_type\":\"%s\"*",
                                               event_type_to_wait_for_.c_str()));
 
       got_right_window_name = base::MatchPattern(
           candidate_event, base::StringPrintf("*\"window_name\":\"%s\"*",
                                               target_frame_name_.c_str()));
     } while (!got_right_event_type || !got_right_window_name);
 
     if (found_event)
       *found_event = candidate_event;
 
     return true;
   }
 
  private:
   std::string target_frame_name_;
   std::string event_type_to_wait_for_;
-  DOMMessageQueue dom_message_queue_;
+  content::DOMMessageQueue dom_message_queue_;
+};
+
+// Helper for verifying contents of DOM events associated with drag-and-drop.
+class DOMDragEventVerifier {
+ public:
+  DOMDragEventVerifier(){};
+
+  void set_expected_drop_effect(const std::string& value) {
+    expected_drop_effect_ = value;
+  }
+
+  void set_expected_effect_allowed(const std::string& value) {
+    expected_effect_allowed_ = value;
+  }
+
+  void set_expected_mime_types(const std::string& value) {
+    expected_mime_types_ = value;
+  }
+
+  // Returns a matcher that will match a std::string (drag event data - e.g.
+  // one returned by DOMDragEventWaiter::WaitForNextMatchingEvent) if it matches
+  // the expectations of this DOMDragEventVerifier.
+  testing::Matcher<std::string> Matches() const {
+    return testing::AllOf(
+        FieldMatches("drop_effect", expected_drop_effect_),
+        FieldMatches("effect_allowed", expected_effect_allowed_),
+        FieldMatches("mime_types", expected_mime_types_));
+  }
+
+ private:
+  static testing::Matcher<std::string> FieldMatches(
+      const std::string& field_name,
+      const std::string& expected_value) {
+    if (expected_value == "<no expectation>")
+      return testing::A<std::string>();
+
+    return testing::HasSubstr(base::StringPrintf(
+        "\"%s\":\"%s\"", field_name.c_str(), expected_value.c_str()));
+  }
+
+  std::string expected_drop_effect_ = "<no expectation>";
+  std::string expected_effect_allowed_ = "<no expectation>";
+  std::string expected_mime_types_ = "<no expectation>";
 };
 
 const char kTestPagePath[] = "/drag_and_drop/page.html";
 
 }  // namespace
 
-class DragAndDropBrowserTest : public ContentBrowserTest {
+class DragAndDropBrowserTest : public InProcessBrowserTest {
  public:
   DragAndDropBrowserTest(){};
 
  protected:
   void SetUpOnMainThread() override {
     host_resolver()->AddRule("*", "127.0.0.1");
     ASSERT_TRUE(embedded_test_server()->Start());
     content::SetupCrossSiteRedirector(embedded_test_server());
-    drag_simulator_.reset(new DragAndDropSimulator(shell()->web_contents()));
+    drag_simulator_.reset(new DragAndDropSimulator(web_contents()));
   }
 
-  // Navigates to content/test/data/drag_and_drop/page.html, with page origin
-  // and frame contents being controlled by the parameters.
-  bool NavigateToTestPage(const std::string& main_origin,
-                          const std::string& left_frame,
-                          const std::string& right_frame) {
-    GURL base_url = embedded_test_server()->GetURL(main_origin, kTestPagePath);
+  content::RenderFrameHost* left_frame() {
+    AssertTestPageIsLoaded();
+    return GetFrameByName("left");
+  }
 
-    std::string left_arg;
-    if (!left_frame.empty()) {
-      left_arg = net::EscapeQueryParamValue(
-          std::string("/cross-site/") + left_frame, true);
-    }
-    std::string right_arg;
-    if (!right_frame.empty()) {
-      right_arg = net::EscapeQueryParamValue(
-          std::string("/cross-site/") + right_frame, true);
-    }
-    std::string query = base::StringPrintf("left=%s&right=%s", left_arg.c_str(),
-                                           right_arg.c_str());
-    GURL::Replacements query_replacement;
-    query_replacement.SetQueryStr(query);
-    GURL target_url = base_url.ReplaceComponents(query_replacement);
+  content::RenderFrameHost* right_frame() {
+    AssertTestPageIsLoaded();
+    return GetFrameByName("right");
+  }
 
-    return NavigateToURL(shell(), target_url);
+  content::WebContents* web_contents() {
+    return browser()->tab_strip_model()->GetActiveWebContents();
   }
 
+  //////////////////////
+  // Navigation helpers.
+
+  bool NavigateToTestPage(const std::string& origin_of_main_frame) {
+    GURL url =
+        embedded_test_server()->GetURL(origin_of_main_frame, kTestPagePath);
+    ui_test_utils::NavigateToURL(browser(), url);
+    return web_contents()->GetLastCommittedURL() == url;
+  }
+
+  // Navigates the left frame to |filename| (found under
+  // chrome/test/data/drag_and_drop directory).
+  bool NavigateLeftFrame(const std::string& origin,
+                         const std::string& filename) {
+    AssertTestPageIsLoaded();
+    return NavigateNamedFrame("left", origin, filename);
+  }
+
+  // Navigates the right frame to |filename| (found under
+  // chrome/test/data/drag_and_drop directory).
+  bool NavigateRightFrame(const std::string& origin,
+                          const std::string& filename) {
+    AssertTestPageIsLoaded();
+    return NavigateNamedFrame("right", origin, filename);
+  }
+
+  ////////////////////////////////////////////////////////////
+  // Simulation of starting a drag-and-drop (using the mouse).
+
+  bool SimulateMouseDownAndDragStartInLeftFrame() {
+    AssertTestPageIsLoaded();
+    if (!SimulateMouseMove(kMiddleOfLeftFrame) || !SimulateMouseDown() ||
+        !SimulateMouseMove(expected_location_of_drag_start_in_left_frame()))
+      return false;
+
+    return true;
+  }
+
+  gfx::Point expected_location_of_drag_start_in_left_frame() {
+    return kMiddleOfLeftFrame + gfx::Vector2d(5, 5);
+  }
+
+  bool SimulateMouseUp() {
+    return ui_test_utils::SendMouseEventsSync(ui_controls::LEFT,
+                                              ui_controls::UP);
+  }
+
+  ////////////////////////////////////////////////////////////////////
+  // Simulation of dragging from outside the browser into web contents
+  // (using DragAndDropSimulator, not simulating mouse events).
+
   bool SimulateDragEnterToRightFrame(const std::string& text) {
     AssertTestPageIsLoaded();
     return drag_simulator_->SimulateDragEnter(kMiddleOfRightFrame, text);
   }
 
   bool SimulateDropInRightFrame() {
     AssertTestPageIsLoaded();
     return drag_simulator_->SimulateDrop(kMiddleOfRightFrame);
   }
 
-  RenderFrameHost* right_frame() {
-    AssertTestPageIsLoaded();
-    return GetFrameByName("right");
+ private:
+  bool SimulateMouseDown() {
+    return ui_test_utils::SendMouseEventsSync(ui_controls::LEFT,
+                                              ui_controls::DOWN);
   }
 
- private:
-  RenderFrameHost* GetFrameByName(const std::string& name_to_find) {
-    WebContentsImpl* web_contents =
-            static_cast<WebContentsImpl*>(shell()->web_contents());
-    FrameTree* frame_tree = web_contents->GetFrameTree();
-    return frame_tree->FindByName(name_to_find)->current_frame_host();
+  bool SimulateMouseMove(const gfx::Point& location_inside_web_contents) {
+    gfx::Rect bounds = web_contents()->GetContainerBounds();
+    return ui_test_utils::SendMouseMoveSync(
+        gfx::Point(bounds.x() + location_inside_web_contents.x(),
+                   bounds.y() + location_inside_web_contents.y()));
+  }
+
+  bool NavigateNamedFrame(const std::string& frame_name,
+                          const std::string& origin,
+                          const std::string& filename) {
+    content::RenderFrameHost* frame = GetFrameByName(frame_name);
+    if (!frame)
+      return false;
+
+    std::string script;
+    int response = 0;
+
+    // Navigate the frame and wait for the load event.
+    script = base::StringPrintf(
+        "location.href = '/cross-site/%s/drag_and_drop/%s';\n"
+        "setTimeout(function() { domAutomationController.send(42); }, 0);",
+        origin.c_str(), filename.c_str());
+    content::TestFrameNavigationObserver observer(frame);
+    if (!content::ExecuteScriptAndExtractInt(frame, script, &response))
+      return false;
+    if (response != 42)
+      return false;
+    observer.Wait();
+
+    // Wait until frame contents (e.g. images) have painted (which should happen
+    // in the animation frame that *starts* after the onload event - therefore
+    // we need to wait for 2 animation frames).
+    script = std::string(
+        "requestAnimationFrame(function() {\n"
+        "  requestAnimationFrame(function() {\n"
+        "    domAutomationController.send(43);\n"
+        "  });\n"
+        "});\n");
+    if (!content::ExecuteScriptAndExtractInt(frame, script, &response))
+      return false;
+    if (response != 43)
+      return false;
+
+    return true;
+  }
+
+  content::RenderFrameHost* GetFrameByName(const std::string& name_to_find) {
+    content::RenderFrameHost* result = nullptr;
+    for (content::RenderFrameHost* rfh : web_contents()->GetAllFrames()) {
+      if (rfh->GetFrameName() == name_to_find) {
+        if (result) {
+          ADD_FAILURE() << "More than one frame named "
+                        << "'" << name_to_find << "'";
+          return nullptr;
+        }
+        result = rfh;
+      }
+    }
+
+    EXPECT_TRUE(result) << "Couldn't find a frame named "
+                        << "'" << name_to_find << "'";
+    return result;
   }
 
   void AssertTestPageIsLoaded() {
-    ASSERT_EQ(kTestPagePath,
-              shell()->web_contents()->GetLastCommittedURL().path());
+    ASSERT_EQ(kTestPagePath, web_contents()->GetLastCommittedURL().path());
   }
 
   std::unique_ptr<DragAndDropSimulator> drag_simulator_;
 
   // Constants with coordinates within content/test/data/drag_and_drop/page.html
   const gfx::Point kMiddleOfLeftFrame = gfx::Point(200, 200);
   const gfx::Point kMiddleOfRightFrame = gfx::Point(400, 200);
 
   DISALLOW_COPY_AND_ASSIGN(DragAndDropBrowserTest);
 };
 
 IN_PROC_BROWSER_TEST_F(DragAndDropBrowserTest, DropTextFromOutside) {
-  ASSERT_TRUE(NavigateToTestPage("a.com",
-                                 "",  // Left frame is unused by this test.
-                                 "c.com/drag_and_drop/drop_target.html"));
+  ASSERT_TRUE(NavigateToTestPage("a.com"));
+  ASSERT_TRUE(NavigateRightFrame("b.com", "drop_target.html"));
 
+  // Setup test expectations.
+  DOMDragEventVerifier expected_dom_event_data;
+  expected_dom_event_data.set_expected_drop_effect("none");
+  expected_dom_event_data.set_expected_effect_allowed("all");
+  expected_dom_event_data.set_expected_mime_types("text/plain");
+
+  // Drag text from outside the browser into/over the right frame.
   {
-    std::string dragover_event;
     DOMDragEventWaiter dragover_waiter("dragover", right_frame());
     ASSERT_TRUE(SimulateDragEnterToRightFrame("Dragged test text"));
+
+    std::string dragover_event;
     ASSERT_TRUE(dragover_waiter.WaitForNextMatchingEvent(&dragover_event));
-    EXPECT_THAT(dragover_event, testing::HasSubstr("\"drop_effect\":\"none\""));
-    EXPECT_THAT(dragover_event,
-                testing::HasSubstr("\"effect_allowed\":\"all\""));
-    EXPECT_THAT(dragover_event,
-                testing::HasSubstr("\"mime_types\":\"text/plain\""));
+    EXPECT_THAT(dragover_event, expected_dom_event_data.Matches());
   }
 
+  // Drop into the right frame.
   {
-    std::string drop_event;
     DOMDragEventWaiter drop_waiter("drop", right_frame());
     ASSERT_TRUE(SimulateDropInRightFrame());
+
+    std::string drop_event;
     ASSERT_TRUE(drop_waiter.WaitForNextMatchingEvent(&drop_event));
-    EXPECT_THAT(drop_event, testing::HasSubstr("\"drop_effect\":\"none\""));
-    EXPECT_THAT(drop_event, testing::HasSubstr("\"effect_allowed\":\"all\""));
-    EXPECT_THAT(drop_event,
-                testing::HasSubstr("\"mime_types\":\"text/plain\""));
+    EXPECT_THAT(drop_event, expected_dom_event_data.Matches());
   }
 }
 
+#if defined(USE_OZONE)

[ncarter (slow), 2016/11/11 20:56:36]

Add a comment explaining why this is disabled in ozone.

[Łukasz Anforowicz, 2016/11/14 17:53:22]

Done.  I've opened https://crbug.com/665042.  I think the fix should be simple,
but I'll postpone it to a follow-up CL, to make sure the test lands as soon as
possible (to help with Paul's efforts + to unblock other CLs like the one to
parametrize tests to test both with same-site and cross-site subframes).

+#define MAYBE_DragStartInFrame DISABLED_DragStartInFrame
+#else
+#define MAYBE_DragStartInFrame DragStartInFrame
+#endif
+IN_PROC_BROWSER_TEST_F(DragAndDropBrowserTest, MAYBE_DragStartInFrame) {
+  std::string frame_site = "b.com";
+  ASSERT_TRUE(NavigateToTestPage("a.com"));
+  ASSERT_TRUE(NavigateLeftFrame(frame_site, "image_source.html"));
+
+  // Setup test expectations.
+  // (dragstart event handler in image_source.html is asking for "copy" only).
+  DOMDragEventVerifier expected_dom_event_data;
+  expected_dom_event_data.set_expected_drop_effect("none");
+  expected_dom_event_data.set_expected_effect_allowed("copy");
+  expected_dom_event_data.set_expected_mime_types(
+      "Files,text/html,text/uri-list");
+
+  // Start the drag in the left frame.
+  DragStartWaiter drag_start_waiter(web_contents());
+  DOMDragEventWaiter dragstart_event_waiter("dragstart", left_frame());
+  EXPECT_TRUE(SimulateMouseDownAndDragStartInLeftFrame());
+
+  // Verify Javascript event data.
+  {
+    std::string dragstart_event;
+    EXPECT_TRUE(
+        dragstart_event_waiter.WaitForNextMatchingEvent(&dragstart_event));
+    EXPECT_THAT(dragstart_event, expected_dom_event_data.Matches());
+  }
+
+  // Verify data being passed to the OS.
+  {
+    std::string text;
+    std::string html;
+    int operation = 0;
+    gfx::Point location_inside_web_contents;
+    EXPECT_TRUE(drag_start_waiter.WaitUntilDragStartIsIntercepted(
+        &text, &html, &operation, &location_inside_web_contents));
+    EXPECT_EQ(embedded_test_server()->GetURL(frame_site,
+                                             "/image_decoding/droids.jpg"),
+              text);
+    EXPECT_THAT(html,
+                testing::MatchesRegex("<img .*src=\""
+                                      "http://.*:.*/image_decoding/droids.jpg"

[ncarter (slow), 2016/11/11 20:56:36]

Technically this could fail if the testserver happened to run on the default
port (the colon would be omitted). That's a non-issue right? The dynamic port
range starts at something like 1000?

[Łukasz Anforowicz, 2016/11/14 17:53:22]

I guess I can get rid of the colon - this will simplify the test a bit without a
big loss in the power the test assertion.

+                                      "\">"));
+    EXPECT_EQ(expected_location_of_drag_start_in_left_frame(),
+              location_inside_web_contents);
+    EXPECT_EQ(ui::DragDropTypes::DRAG_COPY, operation);
+  }
+
+  // Try to leave everything in a clean state.
+  SimulateMouseUp();
+}
+
 }  // namespace chrome