Revert of Moved logic for mapping child process FDs for ICU and V8 into child_process_launcher.cc (patchset #20 id:380001 of https://codereview.chromium.org/1182443003/)

Reason for revert:
Adds new static initializers in http://build.chromium.org/p/chromium/buildstatus?builder=Linux%20x64&number=4979

# icu_util.cc cc::VertexShaderQuadAA::VertexShaderQuadAA()
# icu_util.cc base::MemoryMappedFile::MemoryMappedFile()
# icu_util.cc base::i18n::(anonymous namespace)::g_icudtl_region
# icu_util.cc base::i18n::(anonymous namespace)::g_icudtl_mapped_file
# icu_util.cc operator new(unsigned long)

Original issue's description:
> Moved logic for mapping child process FDs for ICU and V8 into child_process_launcher.cc
>
> Used to be defined in each app's ContentBrowserClient, but since
> content/ is the one that receives the FDs, it makes sense that it should
> be the one to send them.
>
> This also removes ChildProcessLauncher::AppendMappedFileCommandLineSwitches
> as it is no longer needed.
>
> BUG=394502
>
> Committed: https://crrev.com/228414fc8870f88f11ada7512e88ea6999890f56
> Cr-Commit-Position: refs/heads/master@{#334702}

TBR=jochen@chromium.org,jam@chromium.org,jungshik@google.com,michaelbai@chromium.org,rmcilroy@chromium.org,thestig@chromium.org,agrieve@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=394502

Review URL: https://codereview.chromium.org/1187213002

Cr-Commit-Position: refs/heads/master@{#334719}

2 files changed, 62 insertions, 1 deletions

diff --git a/extensions/shell/browser/shell_content_browser_client.cc b/extensions/shell/browser/shell_content_browser_client.cc
index c9314ad..957b830 100644
--- a/extensions/shell/browser/shell_content_browser_client.cc
+++ b/extensions/shell/browser/shell_content_browser_client.cc
@@ -28,6 +28,7 @@
 #include "extensions/shell/browser/shell_browser_main_parts.h"
 #include "extensions/shell/browser/shell_extension_system.h"
 #include "extensions/shell/browser/shell_speech_recognition_manager_delegate.h"
+#include "gin/v8_initializer.h"
 #include "url/gurl.h"
 
 #if !defined(DISABLE_NACL)
@@ -53,7 +54,12 @@ ShellContentBrowserClient* g_instance = nullptr;
 
 ShellContentBrowserClient::ShellContentBrowserClient(
     ShellBrowserMainDelegate* browser_main_delegate)
-    : browser_main_parts_(nullptr),
+    :
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+      v8_natives_fd_(-1),
+      v8_snapshot_fd_(-1),
+#endif  // OS_POSIX && !OS_MACOSX
+      browser_main_parts_(nullptr),
       browser_main_delegate_(browser_main_delegate) {
   DCHECK(!g_instance);
   g_instance = this;
@@ -194,6 +200,21 @@ void ShellContentBrowserClient::SiteInstanceDeleting(
                  site_instance->GetId()));
 }
 
+void ShellContentBrowserClient::AppendMappedFileCommandLineSwitches(
+    base::CommandLine* command_line) {
+  std::string process_type =
+      command_line->GetSwitchValueASCII(::switches::kProcessType);
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+#if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+  DCHECK(natives_fd_exists());
+  command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
+  if (snapshot_fd_exists())
+    command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+#endif  // OS_POSIX && !OS_MACOSX
+}
+
 void ShellContentBrowserClient::AppendExtraCommandLineSwitches(
     base::CommandLine* command_line,
     int child_process_id) {
@@ -233,6 +254,30 @@ void ShellContentBrowserClient::GetAdditionalAllowedSchemesForFileSystem(
   additional_allowed_schemes->push_back(kExtensionScheme);
 }
 
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
+    const base::CommandLine& command_line,
+    int child_process_id,
+    content::FileDescriptorInfo* mappings) {
+#if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+  if (!natives_fd_exists()) {
+    int v8_natives_fd = -1;
+    int v8_snapshot_fd = -1;
+    if (gin::V8Initializer::OpenV8FilesForChildProcesses(&v8_natives_fd,
+                                                         &v8_snapshot_fd)) {
+      v8_natives_fd_.reset(v8_natives_fd);
+      v8_snapshot_fd_.reset(v8_snapshot_fd);
+    }
+  }
+  // V8 can't start up without the source of the natives, but it can
+  // start up (slower) without the snapshot.
+  DCHECK(natives_fd_exists());
+  mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
+  mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+}
+#endif  // OS_POSIX && !OS_MACOSX
+
 content::DevToolsManagerDelegate*
 ShellContentBrowserClient::GetDevToolsManagerDelegate() {
   return new content::ShellDevToolsManagerDelegate(GetBrowserContext());
diff --git a/extensions/shell/browser/shell_content_browser_client.h b/extensions/shell/browser/shell_content_browser_client.h
index 16e51ca..d282397 100644
--- a/extensions/shell/browser/shell_content_browser_client.h
+++ b/extensions/shell/browser/shell_content_browser_client.h
@@ -52,12 +52,21 @@ class ShellContentBrowserClient : public content::ContentBrowserClient {
   void SiteInstanceDeleting(content::SiteInstance* site_instance) override;
   void AppendExtraCommandLineSwitches(base::CommandLine* command_line,
                                       int child_process_id) override;
+  void AppendMappedFileCommandLineSwitches(
+      base::CommandLine* command_line) override;
   content::SpeechRecognitionManagerDelegate*
   CreateSpeechRecognitionManagerDelegate() override;
   content::BrowserPpapiHost* GetExternalBrowserPpapiHost(
       int plugin_process_id) override;
   void GetAdditionalAllowedSchemesForFileSystem(
       std::vector<std::string>* additional_schemes) override;
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+  void GetAdditionalMappedFilesForChildProcess(
+      const base::CommandLine& command_line,
+      int child_process_id,
+      content::FileDescriptorInfo* mappings) override;
+#endif
+
   content::DevToolsManagerDelegate* GetDevToolsManagerDelegate() override;
 
  protected:
@@ -73,6 +82,13 @@ class ShellContentBrowserClient : public content::ContentBrowserClient {
   // Returns the extension or app associated with |site_instance| or NULL.
   const Extension* GetExtension(content::SiteInstance* site_instance);
 
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+  base::ScopedFD v8_natives_fd_;
+  base::ScopedFD v8_snapshot_fd_;
+  bool natives_fd_exists() { return v8_natives_fd_ != -1; }
+  bool snapshot_fd_exists() { return v8_snapshot_fd_ != -1; }
+#endif
+
   // Owned by content::BrowserMainLoop.
   ShellBrowserMainParts* browser_main_parts_;