<webview> Implement clear http cache API.

HTTP cache clearing methods have been refactored into a
separate class: StoragePartitionBrowsingDataRemover in
http://crrev.com/1033013003/

One method was exposed in WebCacheManager so we can
clear renderer/ cache for a given render process.

<webview> already has a set of data it can clear, this
CL adds "cache" to that set, similar to chrome.browsingData
API.

BUG=406437
Test=Load a <webview> in a chrome app, e.g.
the browser sample app:
https://github.com/GoogleChrome/chrome-app-samples/tree/master/samples/webview-samples/browser

Open inspector for the webview: from chrome://inspect,
switch to Apps, and inspect the tab that says "Google"
under "Browser sample". Switch to network tab in that inspector so you can monitor http requests.

Visit some page in the <webview>, for my test case,
I visited http://www.google.ca
Now look at the network tab for image requests (cause it
should be much simpler), e.g. nav_logo_195.png
Reload the page couple of times, observer the status code
for the image request, it should say 304 OK.

Now open the app's inspector: Same as above, but inspect "Browser sample"
instead. Call <webview> clear cache api from its console:

document.querySelector('webview').clearData(
  {since: 1},
  {cache: true},
  function() { window.console.log('clear complete'); })

Expect "clear complete" message to show in app's console.
Now reload the page one more time and check the same
image's request, it should say 200 OK instead of 304.

Review URL: https://codereview.chromium.org/1021073002

Cr-Commit-Position: refs/heads/master@{#322678}

2 files changed, 9 insertions, 0 deletions

diff --git a/components/web_cache/browser/web_cache_manager.cc b/components/web_cache/browser/web_cache_manager.cc
index 4acd209..92aca63 100644
--- a/components/web_cache/browser/web_cache_manager.cc
+++ b/components/web_cache/browser/web_cache_manager.cc
@@ -324,6 +324,12 @@ void WebCacheManager::EnactStrategy(const AllocationStrategy& strategy) {
   }
 }
 
+void WebCacheManager::ClearCacheForProcess(int render_process_id) {
+  std::set<int> renderers;
+  renderers.insert(render_process_id);
+  ClearRendererCache(renderers, INSTANTLY);
+}
+
 void WebCacheManager::ClearRendererCache(
     const std::set<int>& renderers,
     WebCacheManager::ClearCacheOccasion occasion) {
diff --git a/components/web_cache/browser/web_cache_manager.h b/components/web_cache/browser/web_cache_manager.h
index d3ad0a1..0d2d3ff 100644
--- a/components/web_cache/browser/web_cache_manager.h
+++ b/components/web_cache/browser/web_cache_manager.h
@@ -86,6 +86,9 @@ class WebCacheManager : public content::NotificationObserver {
   // Clears all in-memory caches.
   void ClearCache();
 
+  // Instantly clears renderer cache for a process.
+  void ClearCacheForProcess(int process_id);
+
   // Clears all in-memory caches when a tab is reloaded or the user navigates
   // to a different website.
   void ClearCacheOnNavigation();