headless: Implement screenshot capturing

headless/lib/headless_web_contents_browsertest.cc

Index: headless/lib/headless_web_contents_browsertest.cc
diff --git a/headless/lib/headless_web_contents_browsertest.cc b/headless/lib/headless_web_contents_browsertest.cc
index 30faee5e65ef2edf70551c8d55a642af152f4333..7f6bbd0df65a96336ffc77548d415660324d1a04 100644
--- a/headless/lib/headless_web_contents_browsertest.cc
+++ b/headless/lib/headless_web_contents_browsertest.cc
@@ -3,9 +3,14 @@
 // found in the LICENSE file.
 
 #include <memory>
+#include <string>
+#include <vector>
 
 #include "content/public/test/browser_test.h"
+#include "headless/public/domains/page.h"
 #include "headless/public/headless_browser.h"
+#include "headless/public/headless_devtools_client.h"
+#include "headless/public/headless_devtools_target.h"
 #include "headless/public/headless_web_contents.h"
 #include "headless/test/headless_browser_test.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -16,8 +21,51 @@ namespace headless {
 
 class HeadlessWebContentsTest : public HeadlessBrowserTest {};
 
+#define HEADLESS_ASYNC_DEVTOOLED_TEST_F(TEST_FIXTURE_NAME)               \
+  IN_PROC_BROWSER_TEST_F(TEST_FIXTURE_NAME, RunAsyncTest) { RunTest(); } \
+  class AsyncHeadlessBrowserTestNeedsSemicolon##TEST_FIXTURE_NAME {}
+
+class HeadlessAsyncDevTooledBrowserTest : public HeadlessBrowserTest,

[Eric Seckler, 2016/06/02 17:56:32]

I'm following the same pattern as the HeadlessDevToolsClientTest here. If this
is the way to go, I think we might want to move this class (+ the define above)
to headless_browser_test.h/cc and eventually refactor the DevToolsClientTest to
use it as well.

I'm adding this here for now and will move it if you confirm that this is the
correct general direction :)

[Eric Seckler, 2016/06/03 11:30:40]

Moved.

+                                          public HeadlessWebContents::Observer {
+ public:
+  HeadlessAsyncDevTooledBrowserTest()
+      : web_contents_(nullptr),
+        devtools_client_(HeadlessDevToolsClient::Create()) {}
+  ~HeadlessAsyncDevTooledBrowserTest() override {}
+
+  // HeadlessWebContentsObserver implementation:
+  void DevToolsTargetReady() override {
+    EXPECT_TRUE(web_contents_->GetDevToolsTarget());
+    web_contents_->GetDevToolsTarget()->AttachClient(devtools_client_.get());
+    RunDevTooledTest();
+  }
+
+  // Implemented by tests and used to send request(s) to DevTools. Subclasses
+  // need to ensure that FinishAsynchronousTest() is called after response(s)
+  // are processed (e.g. in a callback).
+  virtual void RunDevTooledTest() = 0;
+
+ protected:
+  void RunTest() {
+    web_contents_ =
+        browser()->CreateWebContents(GURL("about:blank"), gfx::Size(800, 600));
+    web_contents_->AddObserver(this);
+
+    RunAsynchronousTest();
+
+    web_contents_->GetDevToolsTarget()->DetachClient(devtools_client_.get());
+    web_contents_->RemoveObserver(this);
+    web_contents_->Close();
+    web_contents_ = nullptr;
+  }
+
+  HeadlessWebContents* web_contents_;
+  std::unique_ptr<HeadlessDevToolsClient> devtools_client_;
+};
+
 IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, Navigation) {
   EXPECT_TRUE(embedded_test_server()->Start());
+
   HeadlessWebContents* web_contents = browser()->CreateWebContents(
       embedded_test_server()->GetURL("/hello.html"), gfx::Size(800, 600));
   EXPECT_TRUE(WaitForLoad(web_contents));
@@ -42,4 +90,23 @@ IN_PROC_BROWSER_TEST_F(HeadlessWebContentsTest, WindowOpen) {
   EXPECT_EQ(static_cast<size_t>(2), all_web_contents.size());
 }
 
+class HeadlessWebContentsScreenshotTest
+    : public HeadlessAsyncDevTooledBrowserTest {
+ public:
+  void RunDevTooledTest() override {
+    devtools_client_->GetPage()->GetExperimental()->CaptureScreenshot(
+        page::CaptureScreenshotParams::Builder().Build(),
+        base::Bind(&HeadlessWebContentsScreenshotTest::OnScreenshotCaptured,
+                   base::Unretained(this)));
+  }
+
+  void OnScreenshotCaptured(
+      std::unique_ptr<page::CaptureScreenshotResult> result) {
+    EXPECT_LT(0U, result->GetData().length());
+    FinishAsynchronousTest();
+  }
+};
+
+HEADLESS_ASYNC_DEVTOOLED_TEST_F(HeadlessWebContentsScreenshotTest);
+
 }  // namespace headless