Delete the non-static CLD data source logic.

components/translate/content/browser/data_file_browser_cld_data_provider.cc

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// NOT DEAD CODE!
-// This code isn't dead, even if it isn't currently being used. Please refer to:
-// https://www.chromium.org/developers/how-tos/compact-language-detector-cld-data-source-configuration
-
-#include "components/translate/content/browser/data_file_browser_cld_data_provider.h"
-
-#include "base/files/file.h"
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/lazy_instance.h"
-#include "base/logging.h"
-#include "base/memory/weak_ptr.h"
-#include "base/synchronization/lock.h"
-#include "base/task_runner.h"
-#include "components/translate/content/common/cld_data_source.h"
-#include "components/translate/content/common/data_file_cld_data_provider_messages.h"
-#include "content/public/browser/browser_thread.h"
-#include "content/public/browser/render_frame_host.h"
-#include "content/public/browser/render_process_host.h"
-#include "content/public/browser/web_contents.h"
-#include "ipc/ipc_message.h"
-#include "ipc/ipc_message_macros.h"
-#include "ipc/ipc_platform_file.h"
-
-namespace {
-// The data file,  cached as long as the process stays alive.
-// We also track the offset at which the data starts, and its length.
-base::LazyInstance<base::FilePath> g_cached_filepath;  // guarded by g_file_lock
-base::File* g_cached_file = NULL;  // guarded by g_file_lock_
-uint64_t g_cached_data_offset = 0;  // guarded by g_file_lock_
-uint64_t g_cached_data_length = 0;  // guarded by g_file_lock_
-
-// Guards g_cached_filepath
-base::LazyInstance<base::Lock> g_file_lock_;
-}  // namespace
-
-namespace translate {
-
-void SetCldDataFilePath(const base::FilePath& path) {
-  VLOG(1) << "Setting CLD data file path to: " << path.value();
-  base::AutoLock lock(g_file_lock_.Get());
-  if (g_cached_filepath.Get() == path)
-    return;  // no change necessary
-  g_cached_filepath.Get() = path;
-  // For sanity, clean these other values up just in case.
-  g_cached_file = NULL;
-  g_cached_data_length = 0;
-  g_cached_data_offset = 0;
-}
-
-base::FilePath GetCldDataFilePath() {
-  base::AutoLock lock(g_file_lock_.Get());
-  if (g_cached_filepath.Get().empty()) {
-    g_cached_filepath.Get() =
-      translate::CldDataSource::Get()->GetCldDataFilePath();
-  }
-  return g_cached_filepath.Get();
-}
-
-DataFileBrowserCldDataProvider::DataFileBrowserCldDataProvider(
-    content::WebContents* web_contents)
-    : web_contents_(web_contents), weak_pointer_factory_() {
-}
-
-DataFileBrowserCldDataProvider::~DataFileBrowserCldDataProvider() {
-  // web_contents_ outlives this object
-}
-
-bool DataFileBrowserCldDataProvider::OnMessageReceived(
-    const IPC::Message& message) {
-  bool handled = true;
-  IPC_BEGIN_MESSAGE_MAP(DataFileBrowserCldDataProvider, message)
-  IPC_MESSAGE_HANDLER(ChromeFrameHostMsg_NeedCldDataFile, OnCldDataRequest)
-  IPC_MESSAGE_UNHANDLED(handled = false)
-  IPC_END_MESSAGE_MAP()
-  return handled;
-}
-
-void DataFileBrowserCldDataProvider::OnCldDataRequest() {
-  // Quickly try to read g_cached_file. If valid, the file handle is
-  // cached and can be used immediately. Else, queue the caching task to the
-  // blocking pool.
-  VLOG(1) << "Received request for CLD data file.";
-  base::File* handle = NULL;
-  uint64_t data_offset = 0;
-  uint64_t data_length = 0;
-  {
-    base::AutoLock lock(g_file_lock_.Get());
-    handle = g_cached_file;
-    data_offset = g_cached_data_offset;
-    data_length = g_cached_data_length;
-  }
-
-  if (handle && handle->IsValid()) {
-    // Cached data available. Respond to the request.
-    VLOG(1) << "CLD data file is already cached, replying immediately.";
-    SendCldDataResponseInternal(handle, data_offset, data_length);
-    return;
-  }
-
-  if (weak_pointer_factory_.get() == NULL) {
-    weak_pointer_factory_.reset(
-        new base::WeakPtrFactory<DataFileBrowserCldDataProvider>(this));
-    weak_pointer_factory_.get()->GetWeakPtr().get();
-  }
-
-  // Else, we don't have the data file yet. Queue a caching attempt.
-  // The caching attempt happens in the blocking pool because it may involve
-  // arbitrary filesystem access.
-  // After the caching attempt is made, we call MaybeSendCLDDataAvailable
-  // to pass the file handle to the renderer. This only results in an IPC
-  // message if the caching attempt was successful.
-  VLOG(1) << "CLD data file not yet cached, deferring lookup";
-  content::BrowserThread::PostBlockingPoolTaskAndReply(
-      FROM_HERE,
-      base::Bind(&DataFileBrowserCldDataProvider::OnCldDataRequestInternal),
-      base::Bind(&DataFileBrowserCldDataProvider::SendCldDataResponse,
-                 weak_pointer_factory_.get()->GetWeakPtr()));
-}
-
-void DataFileBrowserCldDataProvider::SendCldDataResponse() {
-  base::File* handle = NULL;
-  uint64_t data_offset = 0;
-  uint64_t data_length = 0;
-  {
-    base::AutoLock lock(g_file_lock_.Get());
-    handle = g_cached_file;
-    data_offset = g_cached_data_offset;
-    data_length = g_cached_data_length;
-  }
-
-  if (handle && handle->IsValid())
-    SendCldDataResponseInternal(handle, data_offset, data_length);
-}
-
-void DataFileBrowserCldDataProvider::SendCldDataResponseInternal(
-    const base::File* handle,
-    const uint64_t data_offset,
-    const uint64_t data_length) {
-  VLOG(1) << "Sending CLD data file response.";
-
-  content::RenderFrameHost* render_frame_host =
-      web_contents_->GetMainFrame();
-  if (render_frame_host == NULL) {
-    // Render frame destroyed, no need to bother.
-    VLOG(1) << "Lost render frame host, giving up";
-    return;
-  }
-
-  content::RenderProcessHost* render_process_host =
-      render_frame_host->GetProcess();
-  if (render_process_host == NULL) {
-    // Render process destroyed, render frame not yet dead. No need to bother.
-    VLOG(1) << "Lost render process, giving up";
-    return;
-  }
-
-  // Data available, respond to the request.
-  IPC::PlatformFileForTransit ipc_platform_file =
-      IPC::GetPlatformFileForTransit(handle->GetPlatformFile(), false);
-
-  // In general, sending a response from within the code path that is processing
-  // a request is discouraged because there is potential for deadlock (if the
-  // methods are sent synchronously) or loops (if the response can trigger a
-  // new request). Neither of these concerns is relevant in this code, so
-  // sending the response from within the code path of the request handler is
-  // safe.
-  render_frame_host->Send(
-      new ChromeFrameMsg_CldDataFileAvailable(render_frame_host->GetRoutingID(),
-                                             ipc_platform_file,
-                                             data_offset,
-                                             data_length));
-}
-
-void DataFileBrowserCldDataProvider::OnCldDataRequestInternal() {
-  // Because this function involves arbitrary file system access, it must run
-  // on the blocking pool.
-  DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
-  DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
-  VLOG(1) << "CLD data file caching attempt starting.";
-
-  {
-    base::AutoLock lock(g_file_lock_.Get());
-    if (g_cached_file) {
-      VLOG(1) << "CLD data file is already cached, aborting caching attempt";
-      return;  // Already done, duplicate request
-    }
-  }
-
-  const base::FilePath path = GetCldDataFilePath();
-  if (path.empty()) {
-    VLOG(1) << "CLD data file does not yet have a known location.";
-    return;
-  }
-
-  // If the file exists, we can send an IPC-safe construct back to the
-  // renderer process immediately; otherwise, nothing to do here.
-  if (!base::PathExists(path)) {
-    VLOG(1) << "CLD data file does not exist.";
-    return;
-  }
-
-  // Attempt to open the file for reading.
-  std::unique_ptr<base::File> file(
-      new base::File(path, base::File::FLAG_OPEN | base::File::FLAG_READ));
-  if (!file->IsValid()) {
-    LOG(WARNING) << "CLD data file exists but cannot be opened";
-    return;
-  }
-
-  base::File::Info file_info;
-  if (!file->GetInfo(&file_info)) {
-    LOG(WARNING) << "CLD data file exists but cannot be inspected";
-    return;
-  }
-
-  // For now, our offset and length are simply 0 and the length of the file,
-  // respectively. If we later decide to include the CLD2 data file inside of
-  // a larger binary context, these params can be twiddled appropriately.
-  const uint64_t data_offset = 0;
-  const uint64_t data_length = file_info.size;
-
-  {
-    base::AutoLock lock(g_file_lock_.Get());
-    if (g_cached_file) {
-      // Idempotence: Racing another request on the blocking pool, abort.
-      VLOG(1) << "Another thread finished caching first, aborting.";
-    } else {
-      // Else, this request has taken care of it all. Cache all info.
-      VLOG(1) << "Caching CLD data file information.";
-      g_cached_file = file.release();
-      g_cached_data_offset = data_offset;
-      g_cached_data_length = data_length;
-    }
-  }
-}
-
-}  // namespace translate