media::mojom::Remoter and CastRemotingConnector/Sender

chrome/browser/media/router/media_source_helper.cc

Index: chrome/browser/media/router/media_source_helper.cc
diff --git a/chrome/browser/media/router/media_source_helper.cc b/chrome/browser/media/router/media_source_helper.cc
index 9cf7620fe58bc83fab8aab13a3dcf98356488cba..374816d535ab399cb4b48250587fb42302a0e6ec 100644
--- a/chrome/browser/media/router/media_source_helper.cc
+++ b/chrome/browser/media/router/media_source_helper.cc
@@ -4,21 +4,32 @@
 
 #include "chrome/browser/media/router/media_source_helper.h"
 
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/media/router/media_source.h"
+#include "chrome/browser/sessions/session_tab_helper.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "url/gurl.h"
 
 namespace media_router {
 
+namespace {
+
 // Prefixes used to format and detect various protocols' media source URNs.
 // See: https://www.ietf.org/rfc/rfc3406.txt
-const char kTabMediaUrnPrefix[] = "urn:x-org.chromium.media:source:tab";
+const char kTabMediaUrnPrefix[] = "urn:x-org.chromium.media:source:tab:";
 const char kDesktopMediaUrn[] = "urn:x-org.chromium.media:source:desktop";
 const char kCastUrnPrefix[] = "urn:x-com.google.cast:application:";
 
+constexpr size_t kTabMediaUrnPrefixLength = sizeof(kTabMediaUrnPrefix) - 1;
+
+}  // namespace
+
 MediaSource MediaSourceForTab(int tab_id) {
-  return MediaSource(base::StringPrintf("%s:%d", kTabMediaUrnPrefix, tab_id));
+  return MediaSource(base::StringPrintf("%s%d", kTabMediaUrnPrefix, tab_id));
 }
 
 MediaSource MediaSourceForDesktop() {
@@ -58,6 +69,37 @@ bool IsValidMediaSource(const MediaSource& source) {
   return url.is_valid() && url.SchemeIsHTTPOrHTTPS();
 }
 
+content::WebContents* WebContentsFromMediaSource(const MediaSource& source) {
+  if (!IsTabMirroringMediaSource(source))
+    return nullptr;
+
+  // Extract SessionTabHelper ID from the URN.
+  int tab_id = 0;
+  if (!base::StringToInt(
+          base::StringPiece(source.id().begin() + kTabMediaUrnPrefixLength,
+                            source.id().end()),
+          &tab_id)) {
+    return nullptr;
+  }
+
+  // Look-up the WebContents instance associated with the |tab_id|.
+  //
+  // TODO(miu): This is broken for WebContentses that are not associated with
+  // Browser tabs (such as the offscreen presentations provided by the
+  // tabCapture API).
+  for (const Browser* target_browser : *BrowserList::GetInstance()) {
+    TabStripModel* const target_tab_strip = target_browser->tab_strip_model();
+    for (int i = 0; i < target_tab_strip->count(); ++i) {
+      content::WebContents* const contents =
+          target_tab_strip->GetWebContentsAt(i);
+      if (SessionTabHelper::IdForTab(contents) == tab_id)
+        return contents;
+    }
+  }
+
+  return nullptr;
+}
+
 std::string PresentationUrlFromMediaSource(const MediaSource& source) {
   return IsValidPresentationUrl(source.id()) ? source.id() : "";
 }