First cut at "content handling" support in Mojo.

mojo/shell/context.cc

Index: mojo/shell/context.cc
diff --git a/mojo/shell/context.cc b/mojo/shell/context.cc
index 76cc7d6f548bf2cc4219ec0782239d8be05c304d..a6dea440434f5dcb109a1a1622eafb439b8f45e6 100644
--- a/mojo/shell/context.cc
+++ b/mojo/shell/context.cc
@@ -4,10 +4,13 @@
 
 #include "mojo/shell/context.h"
 
+#include <vector>
+
 #include "build/build_config.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_vector.h"
+#include "base/strings/string_split.h"
 #include "mojo/embedder/embedder.h"
 #include "mojo/gles2/gles2_support_impl.h"
 #include "mojo/public/cpp/application/application_impl.h"
@@ -61,6 +64,32 @@ class Setup {
 
 static base::LazyInstance<Setup>::Leaky setup = LAZY_INSTANCE_INITIALIZER;
 
+void InitContentHandlers(DynamicServiceLoader* loader,
+                         base::CommandLine* command_line) {
+  std::string handlers_spec = command_line->GetSwitchValueASCII(
+      switches::kContentHandlers);
+  if (handlers_spec.empty())
+    return;
+
+  std::vector<std::string> parts;
+  base::SplitString(handlers_spec, ',', &parts);
+  if (parts.size() % 2 != 0) {
+    LOG(ERROR) << "Invalid value for switch " << switches::kContentHandlers
+               << ": must be a comma-separated list of mimetype/url pairs.";
+    return;
+  }
+
+  for (size_t i = 0; i < parts.size(); i += 2) {
+    GURL url(parts[i + 1]);
+    if (!url.is_valid()) {
+      LOG(ERROR) << "Invalid value for switch " << switches::kContentHandlers
+                 << ": '" << parts[i + 1] << "' is not a valid URL.";
+      return;
+    }
+    loader->RegisterContentHandler(parts[i], url);
+  }
+}
+
 }  // namespace
 
 class Context::NativeViewportServiceLoader : public ServiceLoader {
@@ -69,10 +98,12 @@ class Context::NativeViewportServiceLoader : public ServiceLoader {
   virtual ~NativeViewportServiceLoader() {}
 
  private:
-  virtual void LoadService(ServiceManager* manager,
-                           const GURL& url,
-                           ScopedMessagePipeHandle shell_handle) OVERRIDE {
-    app_.reset(services::CreateNativeViewportService(shell_handle.Pass()));
+  virtual void Load(ServiceManager* manager,
+                    const GURL& url,
+                    scoped_refptr<LoadCallbacks> callbacks) OVERRIDE {
+    ScopedMessagePipeHandle shell_handle = callbacks->RegisterApplication();
+    if (shell_handle.is_valid())
+      app_.reset(services::CreateNativeViewportService(shell_handle.Pass()));
   }
 
   virtual void OnServiceError(ServiceManager* manager,
@@ -95,16 +126,19 @@ void Context::Init() {
   for (size_t i = 0; i < arraysize(kLocalMojoURLs); ++i)
     mojo_url_resolver_.AddLocalFileMapping(GURL(kLocalMojoURLs[i]));
 
-  base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   scoped_ptr<DynamicServiceRunnerFactory> runner_factory;
-  if (cmdline->HasSwitch(switches::kEnableMultiprocess))
+  if (command_line->HasSwitch(switches::kEnableMultiprocess))
     runner_factory.reset(new OutOfProcessDynamicServiceRunnerFactory());
   else
     runner_factory.reset(new InProcessDynamicServiceRunnerFactory());
 
+  DynamicServiceLoader* dynamic_service_loader =
+      new DynamicServiceLoader(this, runner_factory.Pass());
+  InitContentHandlers(dynamic_service_loader, command_line);
   service_manager_.set_default_loader(
-      scoped_ptr<ServiceLoader>(
-          new DynamicServiceLoader(this, runner_factory.Pass())));
+      scoped_ptr<ServiceLoader>(dynamic_service_loader));
+
   // The native viewport service synchronously waits for certain messages. If we
   // don't run it on its own thread we can easily deadlock. Long term native
   // viewport should run its own process so that this isn't an issue.
@@ -140,9 +174,9 @@ void Context::Init() {
       "dbus");
 #endif  // defined(OS_LINUX)
 
-  if (cmdline->HasSwitch(switches::kSpy)) {
-    spy_.reset(new mojo::Spy(&service_manager_,
-                             cmdline->GetSwitchValueASCII(switches::kSpy)));
+  if (command_line->HasSwitch(switches::kSpy)) {
+    spy_.reset(new mojo::Spy(
+        &service_manager_, command_line->GetSwitchValueASCII(switches::kSpy)));
   }
 
 #if defined(OS_ANDROID)