Avoid using a WebContentsObserver where it is unnecessary.

The DataReductionProxyTabHelper doesn't need to be a WebContentsObserver
to obtain the current associated WebContents because its lifecycle is
tied to the WebContents object. It can just store the WebContents ptr
directly in the object.

BUG=952390

Change-Id: I7246e12212e45bcfe788447a0bf502c2154833c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3145256
Reviewed-by: Robert Ogden <[email protected]>
Commit-Queue: Dave Tapuska <[email protected]>
Cr-Commit-Position: refs/heads/main@{#918851}

Author: dtapuska

chrome/browser/data_reduction_proxy/data_reduction_proxy_tab_helper.cc

@@ -14,7 +14,7 @@
 
 DataReductionProxyTabHelper::DataReductionProxyTabHelper(
     content::WebContents* web_contents)
-    : content::WebContentsObserver(web_contents) {
+    : web_contents_(web_contents) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   drp_settings_ = DataReductionProxyChromeSettingsFactory::GetForBrowserContext(
@@ -40,7 +40,7 @@ void DataReductionProxyTabHelper::OnDataSaverEnabledChanged(bool enabled) {
 }
 
 void DataReductionProxyTabHelper::UpdateWebkitPreferencesNow() {
-  web_contents()->OnWebPreferencesChanged();
+  web_contents_->OnWebPreferencesChanged();
 }
 
 WEB_CONTENTS_USER_DATA_KEY_IMPL(DataReductionProxyTabHelper)

chrome/browser/data_reduction_proxy/data_reduction_proxy_tab_helper.h

@@ -8,14 +8,12 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h"
-#include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 // Tracks when the Data Saver setting is enabled or disabled and notifies
 // content.
 class DataReductionProxyTabHelper
-    : public content::WebContentsObserver,
-      public content::WebContentsUserData<DataReductionProxyTabHelper>,
+    : public content::WebContentsUserData<DataReductionProxyTabHelper>,
       public data_reduction_proxy::DataReductionProxySettingsObserver {
  public:
   ~DataReductionProxyTabHelper() override;
@@ -37,6 +35,8 @@ class DataReductionProxyTabHelper
 
   data_reduction_proxy::DataReductionProxySettings* drp_settings_;
 
+  content::WebContents* const web_contents_;
+
   base::WeakPtrFactory<DataReductionProxyTabHelper> weak_factory_{this};
 
   WEB_CONTENTS_USER_DATA_KEY_DECL();