Default share to Share Target: Partial impl. of Web Share for Desktop.

Currently only shares to a demo Share Target App hosted at
https://wicg.github.io/web-share-target/demos/sharetarget.html;
follow-up CL will have more share options.

BUG=668389

Review-Url: https://codereview.chromium.org/2564483003
Cr-Commit-Position: refs/heads/master@{#443510}

chrome/browser/webshare/share_service_impl.cc

@@ -4,8 +4,44 @@
 
 #include "chrome/browser/webshare/share_service_impl.h"
 
-#include "base/memory/ptr_util.h"
+#include <algorithm>
+#include <functional>
+#include <utility>
+
+#include "base/strings/string_util.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_commands.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/browser_tabstrip.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
+#include "net/base/escape.h"
+
+namespace {
+
+// Determines whether a character is allowed in a URL template placeholder.
+bool IsIdentifier(char c) {
+  return base::IsAsciiAlpha(c) || base::IsAsciiDigit(c) || c == '-' || c == '_';
+}
+
+// Joins a std::vector<base::StringPiece> into a single std::string.
+// TODO(constantina): Implement a base::JoinString() that takes StringPieces.
+// i.e. move this to base/strings/string_util.h, and thoroughly test.
+std::string JoinString(const std::vector<base::StringPiece>& pieces) {
+  size_t total_size = 0;
+  for (const auto& piece : pieces) {
+    total_size += piece.size();
+  }
+  std::string joined_pieces;
+  joined_pieces.reserve(total_size);
+
+  for (const auto& piece : pieces) {
+    piece.AppendToString(&joined_pieces);
+  }
+  return joined_pieces;
+}
+
+}  // namespace
 
 // static
 void ShareServiceImpl::Create(blink::mojom::ShareServiceRequest request) {
@@ -13,11 +49,101 @@ void ShareServiceImpl::Create(blink::mojom::ShareServiceRequest request) {
                           std::move(request));
 }
 
+// static
+bool ShareServiceImpl::ReplacePlaceholders(base::StringPiece url_template,
+                                           base::StringPiece title,
+                                           base::StringPiece text,
+                                           const GURL& share_url,
+                                           std::string* url_template_filled) {
+  constexpr char kTitlePlaceholder[] = "title";
+  constexpr char kTextPlaceholder[] = "text";
+  constexpr char kUrlPlaceholder[] = "url";
+
+  std::map<base::StringPiece, std::string> placeholder_to_data;
+  placeholder_to_data[kTitlePlaceholder] =
+      net::EscapeQueryParamValue(title, false);
+  placeholder_to_data[kTextPlaceholder] =
+      net::EscapeQueryParamValue(text, false);
+  placeholder_to_data[kUrlPlaceholder] =
+      net::EscapeQueryParamValue(share_url.spec(), false);
+
+  std::vector<base::StringPiece> split_template;
+  bool last_saw_open = false;
+  size_t start_index_to_copy = 0;
+  for (size_t i = 0; i < url_template.size(); ++i) {
+    if (last_saw_open) {
+      if (url_template[i] == '}') {
+        base::StringPiece placeholder = url_template.substr(
+            start_index_to_copy + 1, i - 1 - start_index_to_copy);
+        auto it = placeholder_to_data.find(placeholder);
+        if (it != placeholder_to_data.end()) {
+          // Replace the placeholder text with the parameter value.
+          split_template.push_back(it->second);
+        }
+
+        last_saw_open = false;
+        start_index_to_copy = i + 1;
+      } else if (!IsIdentifier(url_template[i])) {
+        // Error: Non-identifier character seen after open.
+        return false;
+      }
+    } else {
+      if (url_template[i] == '}') {
+        // Error: Saw close, with no corresponding open.
+        return false;
+      } else if (url_template[i] == '{') {
+        split_template.push_back(
+            url_template.substr(start_index_to_copy, i - start_index_to_copy));
+
+        last_saw_open = true;
+        start_index_to_copy = i;
+      }
+    }
+  }
+  if (last_saw_open) {
+    // Error: Saw open that was never closed.
+    return false;
+  }
+  split_template.push_back(url_template.substr(
+      start_index_to_copy, url_template.size() - start_index_to_copy));
+
+  *url_template_filled = JoinString(split_template);
+  return true;
+}
+
+void ShareServiceImpl::OpenTargetURL(const GURL& target_url) {
+// TODO(constantina): Prevent this code from being run/compiled in android.
+#if defined(OS_LINUX) || defined(OS_WIN)
+  Browser* browser = BrowserList::GetInstance()->GetLastActive();
+  chrome::AddTabAt(browser, target_url,
+                   browser->tab_strip_model()->active_index() + 1, true);
+#endif
+}
+
 void ShareServiceImpl::Share(const std::string& title,
                              const std::string& text,
-                             const GURL& url,
+                             const GURL& share_url,
                              const ShareCallback& callback) {
-  // TODO(constantina): Implement Web Share Target here.
-  NOTIMPLEMENTED();
-  callback.Run(base::Optional<std::string>("Not implemented: navigator.share"));
+  // TODO(constantina): replace hard-coded URL with one from user-chosen site.
+  constexpr char kUrlBase[] = "https://wicg.github.io/web-share-target/";
+  constexpr char kUrlTemplate[] =
+      "demos/sharetarget.html?title={title}&text={text}&url={url}";
+
+  std::string url_template_filled;
+  if (!ReplacePlaceholders(kUrlTemplate, title, text, share_url,
+                           &url_template_filled)) {
+    callback.Run(base::Optional<std::string>(
+        "Error: unable to replace placeholders in url template"));
+    return;
+  }
+
+  GURL target_url(kUrlBase + url_template_filled);
+  if (!target_url.is_valid()) {
+    callback.Run(base::Optional<std::string>(
+        "Error: url of share target is not a valid url."));
+    return;
+  }
+  OpenTargetURL(target_url);
+
+  callback.Run(base::nullopt);
 }

chrome/browser/webshare/share_service_impl.h

@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "base/gtest_prod_util.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "third_party/WebKit/public/platform/modules/webshare/webshare.mojom.h"
 
@@ -20,12 +21,33 @@ class ShareServiceImpl : public blink::mojom::ShareService {
 
   static void Create(mojo::InterfaceRequest<ShareService> request);
 
+  // blink::mojom::ShareService overrides:
   void Share(const std::string& title,
              const std::string& text,
-             const GURL& url,
+             const GURL& share_url,
              const ShareCallback& callback) override;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(ShareServiceImplUnittest, ReplacePlaceholders);
+
+  // Opens a new tab and navigates to |target_url|.
+  // Virtual for testing purposes.
+  virtual void OpenTargetURL(const GURL& target_url);
+
+  // Writes to |url_template_filled|, a copy of |url_template| with all
+  // instances of "{title}", "{text}", and "{url}" replaced with
+  // |title|, |text|, and |url| respectively.
+  // Replaces instances of "{X}" where "X" is any string besides "title",
+  // "text", and "url", with an empty string, for forwards compatibility.
+  // Returns false, if there are badly nested placeholders.
+  // This includes any case in which two "{" occur before a "}", or a "}"
+  // occurs with no preceding "{".
+  static bool ReplacePlaceholders(base::StringPiece url_template,
+                                  base::StringPiece title,
+                                  base::StringPiece text,
+                                  const GURL& share_url,
+                                  std::string* url_template_filled);
+
   DISALLOW_COPY_AND_ASSIGN(ShareServiceImpl);
 };